Leases - Summary of Capital Lease and Other Financing Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Capitalized Lease [Line Items]
Less current portion	$ (78,705)	$ (101,046)
Noncurrent portion	1,620,256	$ 1,410,742
Capital Lease Obligations
Schedule Of Capitalized Lease [Line Items]
2018	100,815
2019	94,234
2020	94,327
2021	92,455
2022	92,309
Thereafter	801,237
Total minimum lease payments	1,275,377
Plus amount representing residual property value	0
Less amount representing interest	(531,820)
Present value of net minimum lease payments	743,557
Less current portion	(41,117)
Noncurrent portion	702,440
Other Financing Obligations
Schedule Of Capitalized Lease [Line Items]
2018	101,095
2019	88,028
2020	87,758
2021	89,595
2022	90,070
Thereafter	886,277
Total minimum lease payments	1,342,823
Plus amount representing residual property value	545,656
Less amount representing interest	(933,075)
Present value of net minimum lease payments	955,404
Less current portion	(37,588)
Noncurrent portion	917,816
Capital lease and other financing obligations total
Schedule Of Capitalized Lease [Line Items]
2018	201,910
2019	182,262
2020	182,085
2021	182,050
2022	182,379
Thereafter	1,687,514
Total minimum lease payments	2,618,200
Plus amount representing residual property value	545,656
Less amount representing interest	(1,464,895)
Present value of net minimum lease payments	1,698,961
Less current portion	(78,705)
Noncurrent portion	$ 1,620,256