LEASES - Maturity of lease liabilities (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Maturities of lease liabilities
2019 (excluding the nine months ended September 30, 2019)	$ 1,663
2020	6,218
2021	5,387
2022	4,612
2023	3,499
Thereafter	14,933
Total future lease payments	36,312
Less: imputed interest costs	(8,208)
Lease liabilities	$ 28,104