Stock-based Compensation Stock-based Compensation (Details 5) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Weighted-Average Remaining Contractual Term (in years)
Outstanding, beginning of period (in years)	5 years 0 months 0 days	4 years 7 months 6 days
Outstanding, end of period (in years)	5 years 0 months 0 days	4 years 7 months 6 days
Exercisable, end of period (in years)	4 years 0 months 0 days
Vested and expected to vest, end of period (in years)	5 years 0 months 0 days
Stock Option Awards
Shares
Outstanding, beginning of period (in shares)	7,338
Granted (in shares)	608
Exercised (in shares)	(1,439)
Forfeited (in shares)	(53)
Outstanding, end of period (in shares)	6,454
Exercisable, end of period (in shares)	5,232
Vested and expected to vest, end of period (in shares)	6,393
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 22.38
Granted (in dollars per share)	$ 33.86
Exercised (in dollars per share)	$ 19.52
Forfeited (in dollars per share)	$ 33.09
Outstanding, end of period (in dollars per share)	$ 24.01
Exercisable, end of period (in dollars per share)	$ 23.02
Vested and expected to vest, end of period (in dollars per share)	$ 23.97
Aggregate Intrinsic Value
Outstanding, end of period	$ 69,324
Exercisable, end of period	61,455
Vested and expected to vest, end of period	$ 68,931