Share-based Compensation (Stock Option Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, ending balance	1,998,633
Stock options, Exercisable	1,863,633
Stock Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Stock options, Weighted Average Exercise Price, beginning balance (in dollars per share)	$ 2.51	$ 2.22	$ 1.69
Stock options, Granted, Weighted Average Exercise Price (in dollars per share)	$ 16.94	$ 20.58	$ 21.70
Stock options, Exercised, Weighted Average Exercise Price (in dollars per share)	$ 0.75	$ 0.73	$ 4.99
Stock options, Canceled, Weighted Average Exercise Price (in dollars per share)	$ 0	$ 0.72	$ 0
Stock options, Weighted Average Exercise Price, ending balance (in dollars per share)	$ 4.03	$ 2.51	$ 2.22	$ 1.69
Stock options, Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 2.96
Stock Options, Additional Disclosures [Abstract]
Stock options outstanding, Weighted Average Remaining Contractual Term (in years)	1 year 2 months 1 day	1 year 6 months 21 days	2 years 6 months 3 days	2 years 10 months 27 days
Stock options, Exercisable, Weighted Average Remaining Contractual Term (in years)	1 year 0 months 10 days
Stock options outstanding, Aggregate Intrinsic Value	$ 24,171	$ 64,959	$ 71,638	$ 66,344
Stock options, Exercisable, Aggregate Intrinsic Value	24,533
Proceeds from stock options exercised	1,020	51	1,236
Stock Options [Member]
Stock Options, Additional Disclosures [Abstract]
Stock options exercised in period, intrinsic value	$ 24,800	$ 941	$ 5,700
Within Plans [Member]
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, beginning balance	3,315,175	3,340,476	4,542,636
Stock options, Granted	45,000	45,000	45,000
Stock options, Exercised	(1,361,542)	(69,509)	(1,247,160)
Stock options, Canceled	0	(792)	0
Stock options outstanding, ending balance	1,998,633	3,315,175	3,340,476
Stock options, Exercisable	1,863,633
Outside Plan [Member]
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, beginning balance			5,625
Stock options, Exercised			(5,625)
Stock options outstanding, ending balance	0	0	0
Stock options, Exercisable	0