Stock-Based Compensation (Stock Option Activity) (Details) (Stock Options, USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares)	958,246
Options, granted (in shares)	81,328
Options, exercised (in shares)	(153,454)
Options, forfeited (in shares)	(39,243)
Options, outstanding, end of period (in shares)	846,877
Options, vested and expected to vest (in shares)	824,671
Options, exercisable (in shares)	637,782
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, beginning of period (per share)	$ 39.67
Weighted average exercise price, granted (per share)	$ 72.28
Weighted average exercise price, exercised (per share)	$ 36.40
Weighted average exercise price, forfeited (per share)	$ 55.78
Weighted average exercise price, end of period (per share)	$ 42.65
Weighted average exercise price, vested and expected to vest (per share)	$ 42.14
Weighted average exercise price, exercisable (per share)	$ 37.31
Weighted average remaining contractual term (in years)	6 years 2 months 27 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 2 months 1 day
Weighted average remaining contractual term, exercisable (in years)	5 years 5 months 27 days
Options, outstanding, intrinsic value	$ 21,878
Options, vested and expected to vest, intrinsic value	21,683
Options, vested and expected to vest, exercisable	$ 19,650