Consolidated Statement Of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Capital In Excess Of Par Value [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, 2012	$ 468,047	$ 279	$ 467,843	$ (18,495)	$ 7,555	$ 457,182	$ 10,865
Balance, shares at Dec. 31, 2012		27,857,217
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to common stockholders	15,743			15,743	2,231	17,974	180
Comprehensive income	18,154
Distributions to noncontrolling interest	(176)						(176)
Shares issued on stock options exercised, shares		18,959
Shares issued on stock options exercised, value	146	0	146			146
Share-based compensation	1,580		1,580			1,580
Dividends declared, $.695 per share	(19,375)			(19,375)		(19,375)
Balance, value at Mar. 31, 2013	$ 468,376	$ 279	$ 469,569	$ (22,127)	$ 9,786	$ 457,507	$ 10,869
Balance, shares at Mar. 31, 2013	27,876,176	27,876,176