Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Maturities of lease liabilities: Operating lease
2019 (remaining nine months)	$ 227,988
2020	236,511
2021	195,840
2022	126,628
2023	24,628
Thereafter	51,556
Total lease payments	863,151
Less: Imputed interest	(133,776)
Total	729,375
Less: Current portion	(237,533)
Long-term portion of lease obligations	491,842
Maturities of lease liabilities: Finance lease
2019 (remaining nine months)	16,740
2020	22,024
2021	22,026
2022	7,364
Total lease payments	68,154
Less: Imputed interest	(7,402)
Total	60,752	$ 66,984
Less: Current portion	(18,349)
Long-term portion of lease obligations	42,403
Future minimum payments for total lease liabilities
2019 (remaining nine months)	244,728
2020	258,535
2021	217,866
2022	133,992
2023	24,628
Thereafter	51,556
Total lease payments	931,305
Less: Imputed interest	(141,178)
Total	790,127
Less: Current portion	(255,882)
Long-term portion of lease obligations	$ 534,245