Leases - Supplemental balance sheet information related to leases (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Operating Leases
Operating lease right-of-use asset	$ 179,658	$ 183,048
Operating leases liabilities current	16,609	15,862
Operating lease liabilities long-term	170,250	174,327
Total Operating lease liabilities:	186,859	190,189
Finance Leases
Common Plant	1,185	1,488
Other current liabilities	616	669
Other deferred credits	519	811
Total finance lease liabilities	$ 1,135	$ 1,480
Weighted Average Remaining Lease Term
Operating leases	18 years 11 months 4 days	19 years 2 months 26 days
Finance leases	2 years 3 months 14 days	2 years 9 months 3 days
Weighted Average Discount Rate
Operating leases	3.59%	3.59%
Finance leases	2.98%	2.98%