Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common equities	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax				$ 2,503	$ (2,503)
Beginning Balance (Previously Reported) at Dec. 31, 2017				5,180	2,788
Beginning Balance at Dec. 31, 2017		$ 397	$ 1,265	7,683	285	$ (1,387)
Share-based awards		0	(17)			14
Share-based compensation			9
Other			1			1
Net Income (Loss)	$ (31)			(31)
Dividends declared				(87)
Other comprehensive income (loss)	(170)				(170)
Shares acquired - share repurchase authorization						(15)
Shares acquired - share-based compensation plans						(2)
Ending Balance at Mar. 31, 2018	7,946	$ 397	1,258	7,565	115	(1,389)
Beginning Balance (in shares) at Dec. 31, 2017		163.9
Share-based awards (in shares)		0.4
Shares acquired - share repurchase authorization (in shares)		(0.2)
Ending Balance (in shares) at Mar. 31, 2018		164.1
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax					0
Beginning Balance (Previously Reported) at Dec. 31, 2018				7,625	22
Beginning Balance at Dec. 31, 2018	7,833	$ 397	1,281	7,625	22	(1,492)
Share-based awards		0	(14)			13
Share-based compensation			9
Other			1			1
Net Income (Loss)	695			695
Dividends declared				(91)
Other comprehensive income (loss)	188				188
Shares acquired - share repurchase authorization						0
Shares acquired - share-based compensation plans						(5)
Ending Balance at Mar. 31, 2019	$ 8,630	$ 397	$ 1,277	8,229	210	$ (1,483)
Beginning Balance (in shares) at Dec. 31, 2018	198.3	162.8
Share-based awards (in shares)		0.4
Shares acquired - share repurchase authorization (in shares)		0.0
Ending Balance (in shares) at Mar. 31, 2019	198.3	163.2
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax				$ 0	$ 0