Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Income tax benefit from Tax Act	$ 39,000
Remeasurement of U.S. deferred tax liability	130,000
U.S. tax on unremitted earnings	90,916	$ 0	$ 0
Tax benefits from IRS tax settlements and resolution of U.S. tax examinations	30,000	15,000	20,000
Tax benefits from the retroactive effect U.S. tax legislation		58,000	3,000
Valuation allowance on tax attribute carryovers		6,000
Net operating loss carryforwards	287,000
Indefinite lived net operating loss carryforwards	$ 225,000
Operating loss carryforwards, expiration period	15 years
Tax credit carry forwards	$ 82,285	53,181
Tax credit carry forward without expiration	49,000
Unrecognized tax benefits that would affect the effective tax rate if recognized	$ 74,000	104,000	117,000
Possible change to unrecognized tax benefits	25.00%
Interest and penalties	$ (4,000)	1,000	$ (4,000)
Income tax interest and penalties accrued	$ 4,000	$ 9,000
Minimum
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards, expiration period	5 years
Maximum
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards, expiration period	15 years