Income Tax Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Net interest and penalties expense (benefit)	$ 414	$ (746)	$ 1,152	$ (334)
Accrued interest	3,707		3,707		$ 2,706
Accrued penalties	2,396		2,396		2,426
Unrecognized tax benefits related to uncertain tax positions	78,332		78,332		56,702
The amount of unrecognized tax benefits that, if recognized, would affect our effective tax rate	$ 76,958		$ 76,958		$ 55,312