Income Taxes - Effective Income Tax Rate Reconciliation from Continuing Operations (Details)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective income tax rate reconciliation from continuing operations:
United States federal statutory rate	35.00%	35.00%	35.00%
State and local income taxes	0.80%	(0.90%)	(2.60%)
Impact of change in tax contingencies	2.20%	2.40%	(4.20%)
Foreign income tax rate differences	(13.10%)	(14.00%)	(8.40%)
Impact of change in deferred tax asset valuation allowance	1.50%	(7.30%)	(28.60%)
Impact of change in legal entity tax status	0.00%	(5.50%)	0.00%
Impact of non-taxable translation gain	(27.30%)	0.00%	0.00%
Impact of non-taxable interest income	(5.50%)	(4.90%)	(15.60%)
Domestic permanent differences and tax credits	(15.70%)	(5.70%)	(42.10%)
Impact of tax reform	28.60%	0.00%	0.00%
Effective income tax rate reconciliation from continuing operations	6.50%	(0.90%)	(66.50%)

Effective Income Tax Rate Reconciliation, Change in Legal Entity Tax Status, Percent

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Effective Income Tax Rate Reconciliation, Non-Taxable Translation Gain

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Effective Income Tax Rate Reconciliation, Non-taxable Interest Income, Percent

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Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Percent

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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