Consolidated Statement of Shareholders' Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Deferred Equity Compensation [Member]
Beginning balance at Dec. 31, 2015					$ 237
Increase (Decrease) in Shareholders' Equity
Net Income	$ 59
Other comprehensive income	82
Ending balance at Mar. 31, 2016					319
Beginning balance (in shares) at Dec. 31, 2016		127,988,230
Beginning balance at Dec. 31, 2016	6,504	$ 1	$ 1,060	$ 5,289	149	$ 5
Increase (Decrease) in Shareholders' Equity
Net Income	317			317
Dividends ($0.1425 per share)	(18)			(18)
Common stock repurchases (in shares)		(5,430,041)
Common stock repurchases	(216)	$ 0	(216)
Share-based compensation and other (in shares)		470,339
Share-based compensation and other	(7)	$ 0	(3)			(4)
Other comprehensive income	57				57
Ending balance (in shares) at Mar. 31, 2017		123,028,528
Ending balance at Mar. 31, 2017	$ 6,637	$ 1	$ 841	$ 5,588	$ 206	$ 1