Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Contingency [Line Items]
Change in income tax expense - U.S.	$ 18,200
Change in income tax expense	$ (7,700)
Effective income tax rate	11.00%	22.50%	12.80%	22.70%
Income tax expense	$ 2,081	$ 9,753	$ 7,141	$ 29,100