Basis of Presentation (Details 4) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation expense recognized in operating expenses	$ 2,476	$ 2,879
Tax benefit of stock-based compensation expense in provision for income taxes	910	1,048
Stock-based compensation expense, net of tax	1,566	1,831
Fair value of shares vested	2,379	2,813
Proceeds to the Company from the exercise of stock-based compensation	1,769	496
Tax effect from exercise of stock-based compensation, including shortfall tax benefits	(135)	(1,843)
Stock-based compensation cost capitalized in inventory	459	361
Fair Value of Financial Instruments
United States Treasury securities and money market funds included in cash equivalents	99,235	59,074	117,571
Income Taxes
Effective tax rate (as a percent)	38.60%	47.00%
Provision for income taxes	$ 7,604	$ 4,256
1994 Plan
Stock-Based Compensation
Requisite service period for options to vest	4 years
Expiration period for options granted	7 years
Age after which vesting of options granted accelerates if the grantee ceases to be employed by the entity	60 years
2011 Plan
Stock-Based Compensation
Maximum common stock shares that may be issued under plan	16.3