Income Taxes - Summary of Income Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Changes in uncertain income tax positions
Balance, beginning of year	$ 253,277	$ 1,432
Increases in tax positions for prior years	0	251,845
Increases in tax positions for current years	51,738	0
Decreases in tax positions for prior years	(1,432)	0
Balance, end of year	$ 303,583	$ 253,277