Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Liabilities, Other than Long-term Debt, Noncurrent [Abstract]
Tax amortization benefit contingency	$ 30,253	$ 29,369
Lease liability	5,214	0
Other	2,663	2,697
Total other noncurrent liabilities	$ 38,130	$ 32,066