Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail)

v3.6.0.2
Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail) - Subsequent Event [Member]
Jan. 12, 2017
$ / shares
Series A Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.4843749
Series B Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.46875
Series D Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.4375
Senior Common Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.2625
Common Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.375
Dividend Declared for Month of January [Member]  
Dividends Payable [Line Items]  
Record date Jan. 20, 2017
Payment date Jan. 31, 2017
Dividend Declared for Month of January [Member] | Series A Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1614583
Dividend Declared for Month of January [Member] | Series B Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.15625
Dividend Declared for Month of January [Member] | Series D Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1458333
Dividend Declared for Month of January [Member] | Senior Common Stock [Member]  
Dividends Payable [Line Items]  
Payment date Feb. 07, 2017
Month in which distribution is payable to holders of record January
Distributions (in dollars per share) $ 0.0875
Dividend Declared for Month of January [Member] | Common Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.125
Dividend Declared for Month of February [Member]  
Dividends Payable [Line Items]  
Record date Feb. 16, 2017
Payment date Feb. 28, 2017
Dividend Declared for Month of February [Member] | Series A Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1614583
Dividend Declared for Month of February [Member] | Series B Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.15625
Dividend Declared for Month of February [Member] | Series D Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1458333
Dividend Declared for Month of February [Member] | Senior Common Stock [Member]  
Dividends Payable [Line Items]  
Payment date Mar. 07, 2017
Month in which distribution is payable to holders of record February
Distributions (in dollars per share) $ 0.0875
Dividend Declared for Month of February [Member] | Common Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.125
Dividend Declared for Month of March [Member]  
Dividends Payable [Line Items]  
Record date Mar. 22, 2017
Payment date Mar. 31, 2017
Dividend Declared for Month of March [Member] | Series A Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1614583
Dividend Declared for Month of March [Member] | Series B Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) 0.15625
Dividend Declared for Month of March [Member] | Series D Preferred Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.1458333
Dividend Declared for Month of March [Member] | Senior Common Stock [Member]  
Dividends Payable [Line Items]  
Payment date Apr. 07, 2017
Month in which distribution is payable to holders of record March
Distributions (in dollars per share) $ 0.0875
Dividend Declared for Month of March [Member] | Common Stock [Member]  
Dividends Payable [Line Items]  
Distributions (in dollars per share) $ 0.125