Stock-Based Compensation (Details 3) (Stock appreciation rights [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock appreciation rights [Member]
SAR activity under 2005 plan
Shares Outstanding, SARs, Beginning Balance	1,162,705	1,246,495	1,133,352
Granted, SARs	100,914	96,765	136,666
Exercised, SARs	(567,953)	(180,555)	(12,359)
Canceled, SARs	(8,476)		(11,164)
Vested, SARs	1,281,648	1,145,996	834,175
Exercisable, SARs	502,548	930,748	799,482
Shares Outstanding, SARs, Ending Balance	687,190	1,162,705	1,246,495
Outstanding, Weighted Average Grant Price Per Share, Beginning Balance	$ 13.17	$ 13.70	$ 13.25
Weighted-average fair value of grants	$ 25.75	$ 25.76	$ 17.94
Exercised, Weighted Average Grant Price Per Share	$ 13.08	$ 28.34	$ 23.27
Canceled, Weighted Average Grant Price Per Share	$ 24.15		$ 24.02
Vested, Weighted Average Grant Price Per Share	$ 12.48	$ 13.34	$ 14.21
Exercisable, Weighted Average Grant Price Per Share	$ 16.54	$ 14.24	$ 14.41
Outstanding, Weighted Average Grant Price Per Share, Ending Balance	$ 18.56	$ 13.17	$ 13.70