Income Taxes Changes in Balance of Deferred Tax Asset Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Asset Valuation Allowance [Roll Forward]
Beginning Balance	$ (1,213,750)	$ (458,288)	$ (69,900)
Additions	(24,986)	(766,012)	(408,252)
Deductions	90,468	10,550	19,864
Ending Balance	$ (1,148,268)	$ (1,213,750)	$ (458,288)