Stock-based Compensation Stock-based Compensation (Details 5) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Weighted-Average Remaining Contractual Term (in years)
Outstanding, beginning of period (in years)	4 years 8 months 12 days	4 years 7 months 6 days
Outstanding, end of period (in years)	4 years 8 months 12 days	4 years 7 months 6 days
Exercisable, end of period (in years)	3 years 9 months 18 days
Vested and expected to vest, end of period (in years)	4 years 8 months 12 days
Stock Option Awards
Shares
Outstanding, beginning of period (in shares)	7,338
Granted (in shares)	608
Exercised (in shares)	(1,735)
Forfeited (in shares)	(83)
Outstanding, end of period (in shares)	6,128
Exercisable, end of period (in shares)	4,949
Vested and expected to vest, end of period (in shares)	6,069
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)	$ 19.19
Forfeited (in dollars per share)	$ 29.95
Outstanding, end of period (in dollars per share)	$ 24.32
Exercisable, end of period (in dollars per share)	$ 23.36
Vested and expected to vest, end of period (in dollars per share)	$ 24.28
Aggregate Intrinsic Value
Outstanding, end of period	$ 47,251
Exercisable, end of period	42,453
Vested and expected to vest, end of period	$ 47,011