Basis of Presentation (Details 3) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation expense recognized in operating expenses	$ 2,052,000	$ 845,000	$ 5,120,000	$ 2,293,000
Tax benefit of stock-based compensation expense in provision for income taxes	705,000	297,000	1,771,000	818,000
Stock-based compensation expense, net of tax	1,347,000	548,000	3,349,000	1,475,000
Fair value of shares vested	1,895,000	837,000	5,005,000	2,118,000
Proceeds to the Company from the exercise of stock-based compensation	225,000		1,983,000	154,000
Tax benefit from exercise of stock-based compensation, including (shortfall) tax benefits	(54,000)		(56,000)	(39,000)
Stock-based compensation cost capitalized in inventory			229,000	108,000
Fair value of financial instruments
United States Treasury securities and money market funds included in cash equivalents	51,300,000		51,300,000
Income Taxes
Effective tax rate (as a percent)	41.70%	37.60%	43.50%	39.00%
Provision for income taxes	$ 11,347,000	$ 11,754,000	$ 17,719,000	$ 17,016,000
1994 Plan
Stock-Based Compensation
Requisite service period for options to vest			4 years
Expiration period for options granted			P7Y
Age after which vesting of options granted accelerates if the grantee ceases to be employed by the entity			60
2011 Plan
Stock-Based Compensation
Maximum common stock shares that may be issued under plan	16.3		16.3