Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Undistributed earnings of foreign subsidiaries	$ 121,100
Unrecognized deferred tax liability related to undistributed foreign earnings	42,400
R&D tax credit	41,144	$ 29,363	$ 18,655
Deferred federal, state and local tax benefit	45,100
Income tax benefits attributable to the exercise of employee stock options	64,300	79,900	88,900
Unrecognized tax benefits	19,739	17,117	$ 34,812
Reduction in provision for income taxes due to impact of effective tax rate	17,000	$ 13,500
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount	72,500
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount	77,700
Tax credit carryforward not subject to expiration	77,300
Tax credit carryforward subject to expiration	400
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Deferred federal, state and local tax benefit	45,100
Internal Revenue Service (IRS) [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	108,900
Internal Revenue Service (IRS) [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 100,000