Consolidated Statement Of Equity (USD $) In Thousands, except Share data, unless otherwise specified	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, value at Dec. 31, 2013	$ 777,160	$ 330	$ 753,635	$ 3,043	$ 9,538	$ 766,546	$ 10,614
Balance, shares at Dec. 31, 2013	33,051,176	33,051,176
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	72,523			74,080	(2,429)	71,651	872
Distributions to noncontrolling interest	(1,589)						(1,589)
Shares issued on stock options exercised, shares		6,948
Stock Issued During Period, Value, Stock Options Exercised	1	1	0			1
Share-based compensation	1,796		1,796			1,796
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	7,487		7,487			7,487
Dividends declared, $1.54 per share	(76,358)			(76,358)		(76,358)
Balance, value at Sep. 30, 2014	$ 781,020	$ 331	$ 762,918	$ 765	$ 7,109	$ 771,123	$ 9,897
Balance, shares at Sep. 30, 2014	33,058,124	33,058,124