Employee Stock Plans - Stock Option Activity Table (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares outstanding	2,228,108	3,008,520
Shares outstanding, weighted-average exercise price	$ 35.92	$ 32.93
Shares granted	489,779
Shares granted, weighted-average exercise price	$ 41.56
Shares exercised	(1,180,151)
Shares exercised, weighted-average exercise price	$ 30.52
Shares forfeited	(90,040)
Shares forfeited, weighted-average exercise price	$ 37.29
Shares exercisable	1,134,833
Shares exercisable, weighted-average exercise price	$ 32.68
Shares outstanding, weighted-average remaining contractual life	76 months
Shares exercisable, weighted-average remaining contractual life	54 months
Shares outstanding, aggregate intrinsic value	$ 40,834
Shares exercisable, aggregate intrinsic value	$ 24,475