Equity (Distributions) (Detail) (USD $)	0 Months Ended	12 Months Ended
	Dec. 02, 2014	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Common Stock
Dividends Payable [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 1.4000		$ 1.1000		$ 0.9000
Common Stock, Dividends Per Share, Declared, Percentage of Total		100.00%		100.00%		100.00%
Ordinary Income | Common Stock
Dividends Payable [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 1.4000		$ 1.1000		$ 0.9000
Common Stock, Dividends Per Share, Declared, Percentage of Total		100.00%		100.00%		100.00%
Capital Gain | Common Stock
Dividends Payable [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 0.0000		$ 0.0000		$ 0.0000
Common Stock, Dividends Per Share, Declared, Percentage of Total		0.00%		0.00%		0.00%
Return of Capital | Common Stock
Dividends Payable [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 0.0000		$ 0.0000		$ 0.0000
Common Stock, Dividends Per Share, Declared, Percentage of Total		0.00%		0.00%		0.00%
Convertible Preferred Stock Subject to Mandatory Redemption | Preferred Stock
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared	$ 1.3125	$ 2.6688	[1]	$ 0.0000	[2]	$ 0.0000	[2]
Preferred Stock, Dividends Per Share, Declared, Percentage of Total		100.00%		0.00%	[2]	0.00%	[2]
Convertible Preferred Stock Subject to Mandatory Redemption | Ordinary Income | Preferred Stock
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared		$ 2.6688		$ 0.0000	[2]	$ 0.0000	[2]
Preferred Stock, Dividends Per Share, Declared, Percentage of Total		100.00%		0.00%	[2]	0.00%	[2]
Convertible Preferred Stock Subject to Mandatory Redemption | Capital Gain | Preferred Stock
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared		$ 0.0000		$ 0.0000	[2]	$ 0.0000	[2]
Preferred Stock, Dividends Per Share, Declared, Percentage of Total		0.00%		0.00%	[2]	0.00%	[2]
Convertible Preferred Stock Subject to Mandatory Redemption | Return of Capital | Preferred Stock
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared		$ 0.0000		$ 0.0000	[2]	$ 0.0000	[2]
Preferred Stock, Dividends Per Share, Declared, Percentage of Total		0.00%		0.00%	[2]	0.00%	[2]

[1] In addition to the dividends disclosed above, on December 2, 2014, the Company declared a dividend of $1.3125 per share, payable on February 16, 2015 to preferred stockholders of record at the close of business on February 1, 2015.

[2] The Company had no preferred stock outstanding during the years ended December 31, 2013 and 2012.