Summary of Significant Accounting Policies - Schedule of Cumulative Effect of Changes to Opening Balance Sheet from Adoption of ASC 606 (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017
Assets
Accounts receivable, net	$ 781			$ 447
Total current assets	1,524			1,176
Other assets	150			78
Total assets	5,902			5,344
Liabilities and Equity
Accrued royalties	1,509			1,396
Accrued liabilities	409			423
Deferred revenue	170			208
Other current liabilities	153			34
Total current liabilities	2,518			2,373
Deferred tax liabilities, net	230			165
Other noncurrent liabilities	284			307
Total liabilities	6,022			5,664
Equity:
Accumulated deficit	(1,043)			(1,272)
Noncontrolling interest	20			14
Total equity	(120)	$ (139)		(320)	$ 205	$ 321	$ 308
Total liabilities and equity	5,902			$ 5,344
Topic 606
Assets
Accounts receivable, net			$ 704
Total current assets			1,433
Other assets			93
Total assets			5,616
Liabilities and Equity
Accrued royalties			1,475
Accrued liabilities			422
Deferred revenue			181
Other current liabilities			67
Total current liabilities			2,457
Deferred tax liabilities, net			202
Other noncurrent liabilities			308
Total liabilities			5,786
Equity:
Accumulated deficit			(1,133)
Noncontrolling interest			25
Total equity			(170)
Total liabilities and equity			5,616
Impact of Adoption | Topic 606
Assets
Accounts receivable, net	284		257
Total current assets	284		257
Other assets	15		15
Total assets	299		272
Liabilities and Equity
Accrued royalties	95		79
Accrued liabilities	(1)		(1)
Deferred revenue	(28)		(27)
Other current liabilities	30		33
Total current liabilities	96		84
Deferred tax liabilities, net	42		37
Other noncurrent liabilities	4		1
Total liabilities	142		122
Equity:
Accumulated deficit	147		139
Noncontrolling interest	10		11
Total equity	157		150
Total liabilities and equity	$ 299		$ 272