Stock-based Compensation Stock-based Compensation (Details 5) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Weighted-Average Remaining Contractual Term (in years)
Outstanding, beginning of period (in years)	4 years 2 months 12 days	4 years 7 months 6 days
Outstanding, end of period (in years)	4 years 2 months 12 days	4 years 7 months 6 days
Exercisable, end of period (in years)	3 years 3 months 18 days
Vested and expected to vest, end of period (in years)	4 years 2 months 12 days
Stock Option Awards
Shares
Outstanding, beginning of period (in shares)	7,338
Granted (in shares)	0
Exercised (in shares)	(559)
Forfeited (in shares)	(14)
Outstanding, end of period (in shares)	6,765
Exercisable, end of period (in shares)	5,553
Vested and expected to vest, end of period (in shares)	6,704
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 22.38
Granted (in dollars per share)	$ 0.00
Exercised (in dollars per share)	$ 18.00
Forfeited (in dollars per share)	$ 27.33
Outstanding, end of period (in dollars per share)	$ 22.73
Exercisable, end of period (in dollars per share)	$ 22.27
Vested and expected to vest, end of period (in dollars per share)	$ 22.72
Aggregate Intrinsic Value
Outstanding, end of period	$ 88,047
Exercisable, end of period	74,577
Vested and expected to vest, end of period	$ 87,374