Leases - Components of lease expense, and lease assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lease Cost
Amortization of right-to-use assets (included in depreciation expense)	$ 177	$ 178	$ 355	$ 356
Interest on lease liabilities	109	141	227	287
Operating lease cost	3,997	4,232	8,138	8,680
Short-term lease cost	137	121	378	321
Variable lease cost	406	371	916	737
Total lease cost	4,826	$ 5,043	10,014	10,381
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from finance lease			244	303
Operating cash flows from operating leases			7,897	7,447
Financing cash flows from finance lease			642	566
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			4,504	$ 15,206
Assets and Liabilities, Lessee [Abstract]
Finance lease right-of-assets (included in other assets)	$ 1,956		$ 1,956		$ 2,311
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets, net		Other assets, net
Operating lease right-of-use assets	$ 74,170		$ 74,170		76,859
Finance lease liability, current (included in current installments of long-term debt)	$ 1,412		$ 1,412		1,325
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long Term Debt And Capital Lease Obligations Current		Long Term Debt And Capital Lease Obligations Current
Finance lease liability, noncurrent (included in long-term debt)	$ 2,926		$ 2,926		3,654
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long Term Debt And Capital Lease Obligations		Long Term Debt And Capital Lease Obligations
Operating lease liability, current (included in other accrued liabilities)	$ 11,720		$ 11,720		11,043
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current		Other Liabilities, Current
Operating lease liability, noncurrent	$ 64,768		$ 64,768		$ 67,898
Weighted average remaining lease term finance leases	3 years		3 years		3 years 6 months
Weighted average remaining lease term operating leases	9 years 9 months 18 days		9 years 9 months 18 days		10 years 2 months 12 days
Weighted average discount rate finance leases	10.10%		10.10%		10.10%
Weighted average discount rate operating leases	4.70%		4.70%		4.70%