Basis of Presentation - Accounting for Stock-Based Compensation (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation expense recognized in operating expenses	$ 3,141		$ 2,794	$ 8,995	$ 8,869
Less: Tax benefit of stock-based compensation expense in provision for income taxes	1,112		1,005	3,262	3,144
Stock-based compensation expense, net of tax	2,029		1,789	5,733	5,725
Fair value of shares vested	3,088		2,749	9,039	8,744
Proceeds to the Company from the exercise of stock-based compensation	4,166		1,443	6,695	7,019
Tax effect from the exercise of stock-based compensation, including shortfall tax benefits	121	$ (74)	(58)	140	(244)
Fair value of financial instruments
United States Treasury securities and money market funds	$ 13,334	$ 76,047	$ 76,488	$ 13,334	$ 76,488
Income Taxes
Effective tax rate (as a percent)	34.80%		38.40%	35.90%	38.40%
Provision for income taxes	$ 15,898		$ 13,479	$ 40,601	$ 33,115
Stock Compensation Plan
Stock-based compensation activity, including both continuing and discontinued operations
Stock-based compensation cost capitalized in inventory	$ 463		$ 464	$ 463	$ 464
2011 Plan
Stock-Based Compensation
Maximum common stock shares that may be issued under plan (in shares)	16.3			16.3