Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	PreferredStock/Units [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Foreign Currency Adjustment Attributable to Parent [Member]	Series C Preferred Stock [Member]	Series C Preferred Stock [Member] PreferredStock/Units [Member]	Series C Preferred Stock [Member] Additional Paid-in Capital [Member]	Series C Preferred Stock [Member] Retained Earnings [Member]
Balance at Dec. 31, 2013	$ 1,252,274	$ 351,250	$ 65	$ 900,959	$ 0
Balance, shares at Dec. 31, 2013	65,205,274
Net income attributable to controlling interests	$ 105,907				105,907
Dividends declared on common stock	(96,866)			(18,204)	(78,662)
Dividends earned on preferred stock	(27,245)				(27,245)
Redemption of operating partnership units	$ 6,100		0	6,100
Redemption of operating partnership units, shares	234,300
Issuance of stock awards	$ 360		0	360
Issuance of stock awards, shares	163,187
Stock Issued During Period, Value, Stock Options Exercised	$ 5,556		1	5,555
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	507,056
Retirement and forfeiture of stock awards	$ (1,193)		0	(1,193)
Retirement and forfeiture of stock awards, shares	(48,013)
Amortization of deferred compensation costs	$ 6,565			6,565
Adjustments to redeemable noncontrolling interests – operating partnership	(136,117)			(136,117)
Balance at Dec. 31, 2014	$ 1,115,341	351,250	66	764,025	0	$ 0
Balance, shares at Dec. 31, 2014	66,061,804
Net income attributable to controlling interests	$ 1,907				1,907
Dividends declared on common stock	(113,450)			(58,917)	(54,533)
Dividends earned on preferred stock	(27,245)				(27,245)
Redemption of operating partnership units	$ 9,544		0	9,544
Redemption of operating partnership units, shares	363,674
Common stock repurchases	$ (31,912)		(1)	(31,911)
Common stock repurchase, shares	(1,002,610)
Issuance of stock awards	$ 2,239		1	2,238
Issuance of stock awards, shares	565,162
Stock Issued During Period, Value, Stock Options Exercised	$ 7,930		0	7,930
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	362,642
Retirement and forfeiture of stock awards	$ (7,682)		0	(7,682)
Retirement and forfeiture of stock awards, shares	(245,022)
Amortization of deferred compensation costs	$ 7,846			7,846
Adjustments to redeemable noncontrolling interests – operating partnership	(8,105)			(8,105)
Balance at Dec. 31, 2015	956,413	351,250	66	685,042	(79,945)	0
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0			74	(74)
Balance, shares at Dec. 31, 2015	66,105,650
Net income attributable to controlling interests	$ 157,199				157,199
Other comprehensive loss attributable to controlling interests - foreign currency translation adjustments	(1,056)					(1,056)
Stock Issued During Period, Value, New Issues	$ (275,470)		(8)	(275,462)			$ (194,252)	$ (201,250)	$ (6,998)
Stock Issued During Period, Shares, New Issues	7,613,000
Dividends declared on common stock	$ (143,945)			(99,925)	(44,020)
Dividends earned on preferred stock	(20,739)				(20,739)
Redemption of operating partnership units	$ 64,169		2	64,167
Redemption of operating partnership units, shares	1,618,048
Stock Redeemed or Called During Period, Value	$ (351,250)	(351,250)		(12,495)	(12,495)
Issuance of stock awards	$ 810			810
Issuance of stock awards, shares	227,430
Stock Issued During Period, Value, Stock Options Exercised	$ 10,592			10,592
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	478,733
Retirement and forfeiture of stock awards	$ (2,969)			(2,969)
Retirement and forfeiture of stock awards, shares	(128,098)
Amortization of deferred compensation costs	$ 6,813			6,813
Adjustments to redeemable noncontrolling interests – operating partnership	(178,757)			(178,757)
Balance at Dec. 31, 2016	$ 967,002	$ 201,250	$ 76	$ 766,732	$ 0	$ (1,056)
Balance, shares at Dec. 31, 2016	75,914,763