Significant Accounting Policies - Additional Information Related to Leases (Parenthetical) (Details) - USD ($) $ in Millions		9 Months Ended
	Jan. 01, 2019	Sep. 30, 2019
Lessee Disclosure [Abstract]
Operating leases	$ 88	$ 104	[1]
Operating leases commenced amount		$ 16

[1] Amount includes operating leases existing on January 1, 2019 of $88 million and those that commenced during the nine months ended September 30, 2019 of $16 million.