Leases - Summary of Lease Cost and Cash Flow Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lease Cost
Operating lease cost	$ 2,855	$ 2,666	$ 5,902	$ 6,115
Short-term Lease, Cost	2,310	3,734	3,828	6,485
Finance Lease Cost:
Amortization of leased assets	6,424,000	4,418,000	12,397,000	9,912,000
Finance Lease, Interest Expense	920,000	1,142,000	1,925,000	2,249,000
Total finance lease cost	7,344,000	5,560,000	14,322,000	12,161,000
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	5,480	6,400	10,351	12,610
Financing cash flows from finance leases	$ 5,713,000	$ 8,812,000	$ 11,614,000	$ 16,273,000