Leases - Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Right-of-use assets:
Operating	$ 115,647	$ 120,358
Finance	563,350
Total right-of-use assets	678,997
Current:
Operating	17,453
Finance	41,651
Noncurrent liabilities:
Operating	95,215	$ 100,085
Finance	177,293
Total lease liabilities	331,612
Finance lease accumulated amortization	$ 490,000