Consolidated Statement Of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Dividends In Excess Of Net Income [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Parent [Member]	Noncontrolling Interest [Member]
Balance, shares at Dec. 31, 2013		33,051,176
Balance, value at Dec. 31, 2013	$ 777,160	$ 330	$ 753,635	$ 3,043	$ 9,538	$ 766,546	$ 10,614
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	101,609			101,609	(3,315)	98,294	1,443
Comprehensive income	99,737
Distributions to noncontrolling interest	(2,049)						(2,049)
Stock Issued During Period, Shares, New Issues		4,427,500
Stock Issued During Period, Value, New Issues	270,798	$ 44	270,754			270,798
Shares issued on stock options exercised, shares		7,226
Shares issued on stock options exercised, value	(1)	$ (1)				(1)
Share-based compensation	2,020		2,020			2,020
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	7,487		7,487			7,487
Dividends declared, $1.43 per share	(105,221)			(105,221)		(105,221)
Balance, shares at Dec. 31, 2014		37,485,902
Balance, value at Dec. 31, 2014	1,049,933	$ 375	1,033,896	(569)	6,223	1,039,925	10,008
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	148,862			148,862	21,687	170,549	1,452
Comprehensive income	172,001
Distributions to noncontrolling interest	(2,292)						(2,292)
Stock Issued During Period, Shares, New Issues		830,506
Stock Issued During Period, Value, New Issues	49,389	$ 8	49,381			49,389
Payments of Stock Issuance Costs	(275)		275			275
Shares issued on stock options exercised, shares		80,319
Shares issued on stock options exercised, value	(1)	$ (1)				(1)
Share-based compensation	2,134		2,134			2,134
Dividends declared, $1.43 per share	$ (128,431)			(128,431)		(128,431)
Balance, shares at Dec. 31, 2015	38,396,727	38,396,727
Balance, value at Dec. 31, 2015	$ 1,142,460	$ 384	1,085,136	19,862	27,910	1,133,292	9,168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	151,540			151,540	(22,179)	129,361	1,176
Comprehensive income	130,537
Distributions to noncontrolling interest	(1,565)						1,565
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(25,100)		(16,321)			(16,321)	(8,779)
Stock Issued During Period, Shares, New Issues		1,395,642
Stock Issued During Period, Value, New Issues	104,190	$ 14	104,176			104,190
Adjustments Related to Tax Withholding for Share-based Compensation	(1,133)		1,133			1,133
Shares issued on stock options exercised, shares		55,491
Shares issued on stock options exercised, value	(2)	$ 0	(2)			(2)
Share-based compensation	1,732		1,732			1,732
Dividends declared, $1.43 per share	$ (141,529)			(141,529)		(141,529)
Balance, shares at Dec. 31, 2016	39,847,860	39,847,860
Balance, value at Dec. 31, 2016	$ 1,209,590	$ 398	$ 1,173,588	$ 29,873	$ 5,731	$ 1,209,590	$ 0