Leases - Supplemental balance sheet information related to leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Operating Leases
Operating lease right-of-use asset	$ 180,188	$ 183,048
Operating leases liabilities current	16,183	15,862
Operating lease liabilities long-term	170,638	174,327
Total Operating lease liabilities:	186,821	190,189
Finance Leases
Common Plant	1,337	1,488
Other current liabilities	657	669
Other deferred credits	656	811
Total finance lease liabilities	$ 1,313	$ 1,480
Weighted Average Remaining Lease Term
Operating leases	19 years 1 month 13 days	19 years 2 months 26 days
Finance leases	2 years 5 months 23 days	2 years 9 months 3 days
Weighted Average Discount Rate
Operating leases	3.59%	3.59%
Finance leases	2.98%	2.98%