Leases - Balance Sheet Classification of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Property and equipment, net	$ 473,129		$ 640,952
Total finance lease assets	473,129		640,952
Capital lease obligations, current portion			9,817
Other current liabilities	35,725		5,271
Capital lease obligations, excluding current portion			19,658
Construction financing lease obligation, excluding current portion			561,892
Long-term finance lease liabilities	560,381	$ 569,487
Total finance lease liabilities	596,106		$ 596,638
Operating lease assets	60,573	61,674
Other current liabilities	7,520
Long-term operating lease liabilities	63,484	$ 64,849
Total operating lease liabilities	$ 71,004