Leases (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lessee, Lease, Description [Line Items]
Operating	$ 6,163	$ 6,163	$ 0
Current Operating	2,073	2,073
Noncurrent Operating	4,112	4,112	0
Total operating lease liability	6,185	6,185
Lease Costs
Operating lease costs	569	1,158
Short-term lease costs	250	553
Sublease income	(24)	(48)
Net lease costs	$ 795	1,663
Cash paid for amounts included in the measurement of lease liabilities, Operating cash flows from operating leases		1,161
Right-of-use assets obtained in exchange for lease obligations, Operating leases		$ 576
Weighted average discount rate, Operating leases	5.88%	5.88%
Weighted average remaining lease term, Operating leases (in years)	3 years 3 months 18 days	3 years 3 months 18 days
Maturities of Operating Lease Liabilities
Remainder of 2019	$ 1,192	$ 1,192
2020	2,278	2,278
2021	1,684	1,684
2022	1,079	1,079
2023	496	496
After 2023	57	57
Total lease payments	6,786	6,786
Less interest	(601)	(601)
Total operating lease liability	$ 6,185	$ 6,185
Rental payments, minimum rentals and rental expenses			2,081	$ 2,372	$ 2,561
Annual commitments under non-cancellable operating leases, next five years			6,897
Annual commitments under non-cancellable operating lease, after 5 years			55
Maturity of Operating Lease Liabilities
2019			2,224
2020			1,858
2021			1,357
2022			977
2023			481
After 2023			55
Total lease commitments			$ 6,952
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	5 years	5 years