Basis of Presentation (Details 5) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation expense recognized in operating expenses	$ 3,041	$ 2,959	$ 8,781	$ 8,644
Less: Tax benefit of stock-based compensation expense in provision for income taxes	1,075	1,087	3,142	3,031
Stock-based compensation expense, net of tax	1,966	1,872	5,639	5,613
Fair value of shares vested	3,098	3,007	8,789	8,656
Proceeds to the Company from the exercise of stock-based compensation	1,551	4,557	4,178	5,333
Tax effect from the exercise of stock-based compensation, including shortfall tax benefits	(89)	(337)	(275)	(2,187)
Fair value of financial instruments
United States Treasury securities and money market funds included in cash equivalents	98,568	87,381	98,568	87,381	117,571
Income Taxes
Effective tax rate (as a percent)	36.00%	35.20%	36.70%	37.80%
Provision for income taxes	11,577	10,870	30,849	26,304
Stock Compensation Plan
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation cost capitalized in inventory	$ 525	$ 426	$ 525	$ 426
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		16.3