Income Taxes - Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Deferred tax assets:
Net operating loss, capital loss and credits	$ 206	$ 61
Accruals and allowances	209	208
Stock-based compensation	65	88
Net unrealized losses	8	0
Net deferred tax assets	488	357
Valuation allowance	(41)	(25)
Deferred tax assets, net of valuation allowance	447	332
Deferred tax liabilities:
Unremitted foreign earnings	(1,656)	(2,109)	$ (3,000)
Acquisition-related intangibles	(19)	(11)
Depreciation and amortization	(190)	(212)
Available-for-sale securities	(251)	(286)
Other	0	(17)
Deferred tax liabilities	(2,116)	(2,635)
Net deferred tax liabilities	$ (1,669)	$ (2,303)