Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
Right of use assets-operating leases	$ 336,513	$ 326,518
Operating lease liabilities	59,796	56,442
Operating lease liabilities noncurrent	278,303	270,076
Total operating lease liabilities	338,099	326,518
Finance Leases
Accumulated depreciation	(4,512,764)	(4,089,679)
Property, plant and equipment, net, Total	5,373,124	5,016,698
Current maturities of long-term debt	2,082	1,650
Long-term debt	50,999	16,359
Total finance lease liabilities	$ 53,081	$ 18,009
Weighted Average remaining lease term, years
Operating leases	10 years 10 months 24 days	9 years 8 months 12 days
Finance leases	8 years 1 month 6 days	6 years 10 months 24 days
Weighted Average discount rate
Operating leases	4.40%	4.70%
Finance leases	9.70%	9.80%
Finance Lease
Finance Leases
Property and equipment	$ 75,611	$ 38,582
Accumulated depreciation	(28,595)	(26,610)
Property, plant and equipment, net, Total	$ 47,016	$ 11,972