CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member] Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Preferred Stock [Member]	Additional Paid-in Capital [Member] Common Stock [Member]	Cumulated Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive (Loss) [Member]	Total Stockholders' Equity [Member]	Total Stockholders' Equity [Member] Preferred Stock [Member]	Total Stockholders' Equity [Member] Common Stock [Member]	Noncontrolling Interest [Member]
Preferred stock, beginning balance (in shares) at Dec. 31, 2012				0
Common stock, beginning balance (in shares) at Dec. 31, 2012						37,099,209
Beginning balance at Dec. 31, 2012	$ 305,488			$ 0		$ 371		$ 353,861			$ (48,744)	$ 0	$ 305,488			$ 0
Net income	33,715										33,715		33,715
Other comprehensive loss	0
Amortization of stock-based compensation	8,707							8,707					8,707
Stock issuance (in shares)					5,750,000		1,689,536
Stock issuance		$ 138,250	$ 33,896		$ 58		$ 17		$ 138,192	$ 33,879				$ 138,250	$ 33,896
Preferred dividends	(7,966)										(7,966)		(7,966)
Common dividends	(51,926)										(51,926)		(51,926)
Preferred stock, ending balance (in shares) at Dec. 31, 2013				5,750,000
Common stock, ending balance (in shares) at Dec. 31, 2013						38,788,745
Ending balance at Dec. 31, 2013	460,164			$ 58		$ 388		534,639			(74,921)	0	460,164			0
Net income	46,909										46,952		46,952			(43)
Other comprehensive loss	(1,542)											(1,542)	(1,542)
Amortization of stock-based compensation	11,234							11,234					11,234
Stock issuance (in shares)							20,258,256
Stock issuance			507,930				$ 202			507,728					507,930
Preferred dividends	(10,242)										(10,242)		(10,242)
Common dividends	$ (72,630)										(72,630)		(72,630)
Preferred stock, ending balance (in shares) at Dec. 31, 2014	5,750,000			5,750,000
Common stock, ending balance (in shares) at Dec. 31, 2014	59,047,001					59,047,001
Ending balance at Dec. 31, 2014	$ 941,823			$ 58		$ 590		1,053,601			(110,841)	(1,542)	941,866			(43)
Net income	79,383										79,413		79,413			(30)
Other comprehensive loss	(5,791)											(5,791)	(5,791)
Amortization of stock-based compensation	6,946							6,946					6,946
Stock issuance (in shares)							6,135,334
Stock issuance			$ 142,056				$ 62			$ 141,994					$ 142,056
Preferred dividends	(10,242)										(10,242)		(10,242)
Common dividends	(100,478)										(100,478)		(100,478)
Contribution from noncontrolling interest	$ 179															179
Preferred stock, ending balance (in shares) at Dec. 31, 2015	5,750,000			5,750,000
Common stock, ending balance (in shares) at Dec. 31, 2015	65,182,335					65,182,335
Ending balance at Dec. 31, 2015	$ 1,053,876			$ 58		$ 652		$ 1,202,541			$ (142,148)	$ (7,333)	$ 1,053,770			$ 106