Lease Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Capital leased assets [Line Items]
Assets acquired under captial lease, net	$ 4,737	$ 2,676
Capital leases, future minimum payments due, fiscal year maturity [Abstract]
Year ending December 31, 2019	1,426
2020	1,371
2021	1,183
2022	272
2023	71
2024 and after	0
Total minimum lease payments	4,323
Amounts representing interest	116
Present value of net minimum lease payments	4,207
Less current portion	1,345	651
Long-term capital lease obligations, December 31, 2018	2,862	1,859
Operating leases, future minimum payments due, fiscal year maturity [Abstract]
Year ending December 31, 2019	14,023
2020	11,272
2021	7,712
2022	5,129
2023	2,060
2024 and after	1,923
Total minimum lease payments	42,119
Operating leases, rent expense	9,594	7,998	$ 7,536
Equipment [Member]
Capital leased assets [Line Items]
Equipment	6,534	3,481
Less accumulated amortization	$ 1,797	$ 805