Equity and Stock-Based Compensation - Option Rollforward (Details) (USD $)	3 Months Ended		12 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	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]
Beginning Balance		253,342	253,342	303,444
Options Granted	2,192	37,965	40,157	36,835	110,939	165,990
Options Exercised			(177,574)	(75,919)
Options Forfeited			(8,470)	(11,018)
Ending Balance			107,455	253,342	303,444
Options Exerciseable			17,360	98,239
Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price [Abstract]
Outstanding at beginning of year		$ 16.43	$ 16.43	$ 14.19
Options Granted			$ 38.57	$ 37.37
Options Exercised			$ 11.87	$ 18.02
Options Forfeited			$ 29.32	$ 13.67
Outstanding at End of Period			$ 31.23	$ 16.43	$ 14.19
Options Exerciseable			$ 28.81	$ 11.83
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Term, Outstanding			5 years 1 month	4 years 8 months
Weighted Average Remaining Contractual Term, Exercisable			4 years 5 months	4 years 4 months