Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Operating Leases
Right of use assets-operating leases	$ 326,518	$ 0
Operating lease liabilities	56,442	0
Operating lease liabilities noncurrent	270,076	0
Total operating lease liabilities	326,518
Finance Leases
Accumulated depreciation	(4,089,679)	(3,715,515)
Property, plant and equipment, net, Total	5,016,698	$ 4,847,940
Current maturities of long-term debt	1,650
Long-term debt	16,359
Total finance lease liabilities	$ 18,009
Weighted Average remaining lease term, years
Operating leases	9 years 8 months 12 days
Finance leases	6 years 10 months 24 days
Weighted Average discount rate
Operating leases	4.70%
Finance leases	9.80%
Finance Lease
Finance Leases
Property and equipment	$ 38,582
Accumulated depreciation	(26,610)
Property, plant and equipment, net, Total	$ 11,972