Condensed Consolidated Statement of Changes in Stockholders' Equity - 6 months ended Jun. 30, 2017 - USD ($) $ in Millions	Total	Class B Common Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2016	$ 1,502			$ 831	$ 945	$ (77)	$ (197)
Beginning balance, shares at Dec. 31, 2016	131,310,980	12,799,999	134,706,467				(3,395,487)
Net income	$ 40				40
Other comprehensive income	20					20
Issuance of common stock related to exercises of options and vesting of RSUs	3			3
Issuance of common stock related to exercises of options and vesting of RSUs, shares			703,531
Repurchase of common stock	$ (250)						$ (250)
Repurchase of common stock, shares	(6,079,003)						(6,079,003)
Withholding taxes on net share settlements of equity awards	$ (14)			(14)
Stock-based compensation	53			53
Ending balance at Jun. 30, 2017	$ 1,354			$ 873	$ 985	$ (57)	$ (447)
Ending balance, shares at Jun. 30, 2017	125,935,508	12,799,999	135,409,998				(9,474,490)