Condensed Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data	Common Shares [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Shares [Member]	Total
Balances, value at Dec. 31, 2011	$ 5,779	$ 674,498	$ 449,193	$ (13,450)	$ (272)	$ 1,115,748
Balances, shares at Dec. 31, 2011	57,791,000					57,791,000
Stock-based compensation expense		4,723				4,723
Shares repurchased and retired, shares	(2,195,000)
Shares repurchased and retired, value	(219)	(23,590)	(7,578)			(31,387)
Stock options exercised, shares	288,000					288,000
Stock options exercised, value	29	3,432				3,461
Issuance of restricted shares, net of forfeitures, shares	224,000
Issuance of restricted shares, net of forfeitures, value	22	(22)
Excess tax shortfall of stock-based compensation		(35)				(35)
Comprehensive income			38,492	604		39,096
Balances, value at Sep. 30, 2012	$ 5,611	$ 659,006	$ 480,107	$ (12,846)	$ (272)	$ 1,131,606
Balances, shares at Sep. 30, 2012	56,108,000					56,108,000