LEASES (Tables)

9 Months Ended

Sep. 30, 2020

Leases [Abstract]

Schedule of components of lease expense

The components of lease expense for the three and nine months ended September 30, 2020 and 2019 were as follows:​

​	Three Months Ended September 30,				Nine Months Ended September 30,
​	2020		2019		2020		2019
Operating lease cost	$	6,076	$	6,001	$	17,171	$	17,442
Finance lease cost:	​		​		​		​
Amortization of right-of-use assets	$	905	$	1,165	$	3,010	$	3,041
Interest on lease liabilities	$	356	$	344	$	1,073	$	984
Total finance lease cost	$	1,261	$	1,509	$	4,083	$	4,025
Short-term lease and variable lease costs	$	2,466	$	1,757	$	7,344	$	6,027

Schedule of supplemental cash flow information related to leases

Supplemental cash flow information related to leases was as follows:

Nine Months Ended September 30,	2020		2019
Cash paid for amounts included in the measurement of lease liabilities:	​		​
Operating cash flows from operating leases	$	17,060	$	15,874
Operating cash flows from finance leases	1,089		877
Financing cash flows from finance leases	3,678		3,365
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	19,255	$	11,673
Finance leases	3,356		12,401