Stock Compensation Stock Compensation Stock Option Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Jan. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding (in shares)	2,537,601	2,308,004		2,537,601		2,550,048
Granted (in shares)		0		503,843		115,763
Exercised (in shares)	(448,960)	(16,079)		(531,321)		(128,189)
Cancelled (in shares)		(6,285)		(202,119)		(21)
Outstanding (in shares)		2,285,640		2,308,004		2,537,601		2,550,048
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.74	$ 13.10		$ 12.74		$ 12.53
Granted, Weighted Average Exercise Price (in dollars per share)		$ 0.00		$ 15.58		$ 14.18
Exercised, Weighted Average Exercise Price (in dollars per share)		$ 8.66		$ 10.85		$ 9.87
Cancelled, Weighted Average Exercise Price (in dollars per share)		$ 15.07		$ 0.00		$ 0.00
Outstanding, Weighted Average Exercise Price (in dollars per share)		$ 13.12		$ 13.10		$ 12.74		$ 12.53
Outstanding, Weighted Average Remaining Contractual Term		6 years 7 months 6 days		7 years 7 months 6 days		6 years		6 years 7 months 6 days
Outstanding, Aggregate Intrinsic Value		$ 4,371	[1]	$ 11,187	[1]	$ 11,208	[1]	$ 1,947	[1]
Options exercisable (in shares)		398,437		391,859		1,118,264
Common stock fair value		$ 14.87		$ 16.91		$ 15.71

[1] The aggregate intrinsic value represents the amount by which the fair value of the underlying common stock ($14.87, $16.91 and $15.71 at December 31, 2012, 2011 and 2010, respectively) exceeds the option exercise price.