Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating Leases
Right of use assets-operating leases	$ 342,032	$ 0
Operating lease liabilities	56,136	0
Operating lease liabilities noncurrent	286,101	0
Total operating lease liabilities	342,237
Finance Leases
Property and equipment	8,733,367	8,563,455
Less: accumulated depreciation	(3,818,529)	(3,715,515)
Property, plant and equipment, net, Total	4,914,838	$ 4,847,940
Current maturities of long-term debt	1,737
Long-term debt	17,612
Total finance lease liabilities	$ 19,349
Weighted Average remaining lease term, years
Operating leases	10 years 4 months 24 days
Finance leases	7 years 9 months 18 days
Weighted Average discount rate
Operating leases	4.70%
Finance leases	10.50%
Finance Lease
Finance Leases
Property and equipment	$ 23,250
Less: accumulated depreciation	(9,882)
Property, plant and equipment, net, Total	$ 13,368