Goodwill and Acquisition-Related Intangibles - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, net	$ 4,362,000,000		$ 4,362,000,000		$ 4,362,000,000
Goodwill impairment loss			0	$ 0
Amortization of acquisition-related intangibles	$ 80,000,000	$ 80,000,000	$ 239,000,000	$ 239,000,000