Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Total stockholder's equity at beginning of period at Dec. 31, 2017		$ 683,000,000	$ 2,175,000,000	$ 9,364,000,000	$ 16,000,000	$ (60,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			4,000,000			2,000,000
Dividends to common stockholders ($0.35, $0.30, $2.70 and $2.60 per share)				(709,000,000)
Net income	$ 561,000,000			561,000,000
Other comprehensive income (loss)	(621,000,000)				(621,000,000)
Purchase of treasury stock						0
Total stockholder's equity at end of period at Jun. 30, 2018	11,415,000,000	683,000,000	2,179,000,000	9,216,000,000	(605,000,000)	(58,000,000)
Total stockholder's equity at beginning of period at Dec. 31, 2017		683,000,000	2,175,000,000	9,364,000,000	16,000,000	(60,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchase of treasury stock	0
Total stockholder's equity at end of period at Dec. 31, 2018	11,217,000,000	683,000,000	2,192,000,000	9,277,000,000	(878,000,000)	(57,000,000)
Total stockholder's equity at beginning of period at Mar. 31, 2018		683,000,000	2,173,000,000	9,028,000,000	(400,000,000)	(59,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			6,000,000			1,000,000
Dividends to common stockholders ($0.35, $0.30, $2.70 and $2.60 per share)				(82,000,000)
Net income	270,000,000			270,000,000
Other comprehensive income (loss)	(205,000,000)				(205,000,000)
Purchase of treasury stock						0
Total stockholder's equity at end of period at Jun. 30, 2018	11,415,000,000	683,000,000	2,179,000,000	9,216,000,000	(605,000,000)	(58,000,000)
Total stockholder's equity at beginning of period at Dec. 31, 2018	11,217,000,000	683,000,000	2,192,000,000	9,277,000,000	(878,000,000)	(57,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			(2,000,000)			8,000,000
Dividends to common stockholders ($0.35, $0.30, $2.70 and $2.60 per share)				(738,000,000)
Net income	620,000,000			620,000,000
Other comprehensive income (loss)	998,000,000				998,000,000
Purchase of treasury stock	(16,000,000)					(16,000,000)
Total stockholder's equity at end of period at Jun. 30, 2019	12,087,000,000	683,000,000	2,190,000,000	9,159,000,000	120,000,000	(65,000,000)
Total stockholder's equity at beginning of period at Mar. 31, 2019		683,000,000	2,184,000,000	8,976,000,000	(324,000,000)	(64,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			6,000,000			1,000,000
Dividends to common stockholders ($0.35, $0.30, $2.70 and $2.60 per share)				(95,000,000)
Net income	278,000,000			278,000,000
Other comprehensive income (loss)	444,000,000				444,000,000
Purchase of treasury stock						(2,000,000)
Total stockholder's equity at end of period at Jun. 30, 2019	$ 12,087,000,000	$ 683,000,000	$ 2,190,000,000	$ 9,159,000,000	$ 120,000,000	$ (65,000,000)