Leases - Components of lease expense, and lease assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Lease Cost
Amortization of right-to-use assets (included in depreciation expense)	$ 178
Interest on lease liabilities	146
Operating lease cost	4,448
Short-term lease cost	200
Variable lease cost	366
Total lease cost	5,338
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from finance lease	157
Operating cash flows from operating leases	3,835
Financing cash flows from finance lease	273
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	660
Assets and Liabilities, Lessee [Abstract]
Finance lease right-of-assets (included in other assets)	$ 2,845
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other, net
Operating lease right-of-use assets	$ 81,159	$ 0
Finance liability, current (included in current installments of long-term debt)	$ 1,206
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long Term Debt And Capital Lease Obligations Current
Finance lease liability, noncurrent (included in long-term debt)	$ 4,668
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long Term Debt And Capital Lease Obligations
Operating lease liability, current (included in other accrued liabilities)	$ 11,889
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current
Operating lease liability, noncurrent	$ 70,859	$ 0
Weighted average remaining lease term finance leases	4 years
Weighted average remaining lease term operating leases	9 years 6 months 25 days
Weighted average discount rate finance leases	10.10%
Weighted average discount rate operating leases	4.63%