Consolidated Statement Of Equity - 3 months ended Mar. 31, 2016 - 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, 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 (Loss) Attributable to Parent	32,725			32,725	(1,642)		384
Comprehensive income	31,467					31,083
Distributions to noncontrolling interest	(435)						435
Adjustments Related to Tax Withholding for Share-based Compensation	(219)		219			219
Shares issued on stock options exercised, shares		7,251
Share-based compensation	979		979			979
Dividends declared, $1.54 per share	$ (34,563)			(34,563)		(34,563)
Balance, shares at Mar. 31, 2016	38,403,978	38,403,978
Balance, value at Mar. 31, 2016	$ 1,139,689	$ 384	$ 1,085,896	$ 18,024	$ 26,268	$ 1,130,572	$ 9,117