Stock-Based Compensation (Details) (USD $)	Dec. 03, 2012 Stock Options [Member]	Sep. 04, 2012 Stock Options [Member]	Jun. 01, 2012 Stock Options [Member]	Mar. 01, 2012 Stock Options [Member]	Dec. 03, 2012 Stock Options [Member] Director [Member]	Sep. 04, 2012 Stock Options [Member] Director [Member]	Jun. 01, 2012 Stock Options [Member] Director [Member]	Mar. 01, 2012 Stock Options [Member] Director [Member]	Dec. 31, 2012 2008 Equity and Incentive Plan	Dec. 31, 2012 2008 Equity and Incentive Plan Grant Awards, Other than Options, or Stock Appreciation Rights [Member]	Dec. 31, 2012 Stock Options Annual Grant, 2012 [Member] Restricted Stock [Member]		Dec. 31, 2012 Stock Options Annual Grant, 2012 [Member] Stock Options [Member]	Dec. 31, 2012 Non-Employee Director Plan [Member] Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized									12,000,000	2,000,000	200,000	[1]	900,000	2,000,000
Percentage of total stock option award granted on specific date	25.00%	25.00%	25.00%	25.00%
Automatic grant of options to purchase common stock (per non-employee director)					5,000	5,000	5,000	5,000
Exercise price of options to purchase common stock granted	$ 38.63	$ 41.16	$ 35	$ 34.09

[1] The restricted stock awards granted during 2012 are primarily related to our employee annual restricted stock award grant in March 2012.