Accumulated Other Comprehensive Income (Loss) by Component Schedule of Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2017	Jan. 01, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	$ 12,244	$ 12,244	$ 11,969
Other comprehensive income (loss) before reclassifications		(922)	262
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		(28)	57
Other comprehensive income (loss) after tax (expense) benefit		(894)	205
Total stockholder's equity at end of period		11,217	12,244
Reclassification from AOCI, tax		8	24
Tax (expense) benefit on other comprehensive income (loss)		216	(75)
Net unrealized gains (losses) on investments with OTTI losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	25	25	30
Total stockholders equity, adjusted balance	30
Other comprehensive income (loss) before reclassifications		(7)	(3)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		7	2
Other comprehensive income (loss) after tax (expense) benefit		(14)	(5)
Total stockholder's equity at end of period		16	25
Reclassification from AOCI, tax		(2)	1
Tax (expense) benefit on other comprehensive income (loss)		4	2
Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	750	750	642
Total stockholders equity, adjusted balance	859
Other comprehensive income (loss) before reclassifications		(801)	190
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		(3)	82
Other comprehensive income (loss) after tax (expense) benefit		(798)	108
Total stockholder's equity at end of period		61	750
Reclassification from AOCI, tax		2	38
Tax (expense) benefit on other comprehensive income (loss)		211	(68)
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(645)	(645)	(647)
Total stockholders equity, adjusted balance	(775)
Other comprehensive income (loss) before reclassifications		(32)	(25)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		(32)	(27)
Other comprehensive income (loss) after tax (expense) benefit		0	2
Total stockholder's equity at end of period		(775)	(645)
Reclassification from AOCI, tax		8	(15)
Tax (expense) benefit on other comprehensive income (loss)		1	(9)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(98)	(98)	(198)
Total stockholders equity, adjusted balance	(98)
Other comprehensive income (loss) before reclassifications		(82)	100
Amounts reclassified from accumulated other comprehensive income (loss) net of tax		0	0
Other comprehensive income (loss) after tax (expense) benefit		(82)	100
Total stockholder's equity at end of period		(180)	(98)
Reclassification from AOCI, tax		0	0
Tax (expense) benefit on other comprehensive income (loss)		0	0
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	32	32	(173)
Cumulative effect adjustments from changes in accounting guidance, net of tax	(16)			$ 0	$ 0
Total stockholders equity, adjusted balance	16
Total stockholder's equity at end of period	16	$ (878)	$ 32
ASU 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	12
ASU 2018-02 | Net unrealized gains (losses) on investments with OTTI losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	5
ASU 2018-02 | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	137
ASU 2018-02 | Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	(130)
ASU 2018-02 | Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	0
ASU 2018-02 | Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	12
ASU 2016-01
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	(28)
Cumulative effect, Tax	8
ASU 2016-01 | Net unrealized gains (losses) on investments with OTTI losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	0
Cumulative effect, Tax	0
ASU 2016-01 | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	(28)
Cumulative effect, Tax	8
ASU 2016-01 | Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	0
Cumulative effect, Tax	0
ASU 2016-01 | Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cumulative effect adjustments from changes in accounting guidance, net of tax	0
Cumulative effect, Tax	$ 0