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	$ 205
Other comprehensive income	146
Ending balance at Jun. 30, 2016					383
Beginning balance at Mar. 31, 2016					319
Increase (Decrease) in Shareholders' Equity
Net Income	146
Other comprehensive income	64
Ending balance at Jun. 30, 2016					383
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	470			470
Dividends ($0.285 per share)	(36)			(36)
Common stock repurchases (in shares)		(8,886,752)
Common stock repurchases	(351)	$ 0	(351)
Share-based compensation and other (in shares)		567,381
Share-based compensation and other	(2)	$ 0	2			(4)
Other comprehensive income	166				166
Other	(1)			(1)
Ending balance (in shares) at Jun. 30, 2017		119,668,859
Ending balance at Jun. 30, 2017	6,750	$ 1	711	5,722	315	1
Beginning balance at Mar. 31, 2017					206
Increase (Decrease) in Shareholders' Equity
Net Income	153
Other comprehensive income	109
Ending balance (in shares) at Jun. 30, 2017		119,668,859
Ending balance at Jun. 30, 2017	$ 6,750	$ 1	$ 711	$ 5,722	$ 315	$ 1