Stock-Based Compensation (Stock Option Activity) (Details) (Stock Options, USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares)	775,059
Options, granted (in shares)	117,424
Options, exercised (in shares)	(221,725)
Options, forfeited (in shares)	(1,889)
Options, outstanding, end of period (in shares)	668,869
Options, vested and expected to vest (in shares)	634,658
Options, exercisable (in shares)	451,812
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)	$ 42.09
Weighted average exercise price, granted (per share)	$ 81.57
Weighted average exercise price, exercised (per share)	$ 29.87
Weighted average exercise price, forfeited (per share)	$ 72.28
Weighted average exercise price, end of period (per share)	$ 52.99
Weighted average exercise price, vested and expected to vest (per share)	$ 51.77
Weighted average exercise price, exercisable (per share)	$ 44.17
Weighted average remaining contractual term (in years)	6 years 8 months 26 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 7 months 2 days
Weighted average remaining contractual term, exercisable (in years)	5 years 6 months 27 days
Options, outstanding, intrinsic value	$ 17,200
Options, vested and expected to vest, intrinsic value	17,000
Options, vested and expected to vest, exercisable	$ 15,300