Income Taxes - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Feb. 28, 2018	Feb. 29, 2016	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Remeasurement of net deferred tax liabilities			$ 140,000
Income tax receivable, related to carrybacks				$ 14,500
Income taxes receivable, related to overpayments				5,400
Income tax receivable			100,023	29,148	$ 100,023
Proceeds from refund of overpaid federal tax	$ 77,000	$ 120,000
Uncertain tax benefits that, if recognized, would affect effective tax rate			$ 1,700	2,500	1,700
Recognized interest and penalties expense (benefit) related to unrecognized tax benefits				100	$ 600	$ 100
Accrued interest and penalties				300
State Tax
Operating Loss Carryforwards [Line Items]
Tax credit carryforward				6,900
Federal Tax
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards				$ 267,000