Consolidating Financial Statements (Details) - Consolidating Balance Sheet (Unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Consolidating Balance Sheet
Fixed maturities, at fair value	$ 65,500	$ 63,464
Equity securities, at fair value	400	368
Real estate investments	969	904
Short-term securities	4,094	3,985
Other investments	3,554	3,557
Total investments	74,517	72,278
Cash	357	373	$ 397	$ 344
Investment income accrued	591	624
Premiums receivable	7,947	7,506
Reinsurance recoverables	8,281	8,370
Ceded unearned premiums	935	578
Deferred acquisition costs	2,190	2,120
Deferred taxes	115	445
Contractholder receivables	4,811	4,785
Goodwill	3,949	3,937
Other intangible assets	341	345
Other assets	3,212	2,872
Total assets	107,246	104,233
Claims and claim adjustment expense reserves	50,718	50,668
Unearned premium reserves	14,122	13,555
Contractholder payables	4,811	4,785
Payables for reinsurance premiums	635	289
Debt	7,057	6,564
Other liabilities	5,563	5,478
Total liabilities	82,906	81,339
Common stock	23,243	23,144
Retained earnings	35,795	35,204
Accumulated other comprehensive income (loss)	(682)	(1,859)
Treasury stock, at cost	(34,016)	(33,595)
Total shareholders’ equity	24,340	22,894	22,979
Total liabilities and shareholders’ equity	107,246	104,233
Fixed maturities, available for sale, amortized cost	64,216	63,601
Equity securities, cost	$ 375	$ 382
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000.0
Common stock, shares issued (in shares)	262,000,000	263,700,000
Common stock, shares outstanding (in shares)	261,900,000	263,600,000
Treasury stock, at cost (in shares)	514,200,000	510,900,000
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	$ 45,336	$ 43,683
Equity securities, at fair value	105	105
Real estate investments	1	2
Short-term securities	1,645	1,855
Other investments	2,772	2,746
Total investments	49,859	48,391
Cash	150	181	175	157
Investment income accrued	406	434
Premiums receivable	5,356	5,089
Reinsurance recoverables	6,496	5,904
Ceded unearned premiums	838	522
Deferred acquisition costs	1,987	1,930
Deferred taxes	(76)	167
Contractholder receivables	4,801	3,867
Goodwill	2,581	2,578
Other intangible assets	222	224
Other assets	2,470	2,220
Total assets	75,090	71,507
Claims and claim adjustment expense reserves	34,800	34,093
Unearned premium reserves	9,872	9,414
Contractholder payables	4,801	3,867
Payables for reinsurance premiums	380	169
Debt	693	693
Other liabilities	4,287	4,133
Total liabilities	54,833	52,369
Additional paid-in capital	11,634	11,634
Retained earnings	8,390	8,065
Accumulated other comprehensive income (loss)	233	(561)
Total shareholders’ equity	20,257	19,138
Total liabilities and shareholders’ equity	75,090	71,507
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	20,079	19,697
Equity securities, at fair value	106	92
Real estate investments	968	902
Short-term securities	581	759
Other investments	781	810
Total investments	22,515	22,260
Cash	207	192	221	$ 187
Investment income accrued	182	187
Premiums receivable	2,591	2,417
Reinsurance recoverables	1,785	2,466
Ceded unearned premiums	97	56
Deferred acquisition costs	203	190
Deferred taxes	222	302
Contractholder receivables	10	918
Goodwill	1,377	1,368
Other intangible assets	119	121
Other assets	393	15
Total assets	29,701	30,492
Claims and claim adjustment expense reserves	15,918	16,575
Unearned premium reserves	4,250	4,141
Contractholder payables	10	918
Payables for reinsurance premiums	255	120
Debt		32
Other liabilities	1,049	849
Total liabilities	21,482	22,635
Common stock	401	401
Additional paid-in capital	7,083	7,023
Retained earnings	807	879
Accumulated other comprehensive income (loss)	(72)	(446)
Total shareholders’ equity	8,219	7,857
Total liabilities and shareholders’ equity	29,701	30,492
Reportable Legal Entities [Member] | TRV [Member]
Consolidating Balance Sheet
Fixed maturities, at fair value	85	84
Equity securities, at fair value	189	171
Short-term securities	1,868	1,371
Other investments	1	1
Total investments	2,143	1,627
Cash			$ 1
Investment income accrued	3	3
Deferred taxes	(31)	(24)
Investment in subsidiaries	28,475	26,993
Other assets	349	669
Total assets	30,939	29,268
Debt	6,364	5,871
Other liabilities	227	496
Total liabilities	6,591	6,367
Common stock	23,243	23,144
Retained earnings	35,803	35,211
Accumulated other comprehensive income (loss)	(682)	(1,859)
Treasury stock, at cost	(34,016)	(33,595)
Total shareholders’ equity	24,348	22,901
Total liabilities and shareholders’ equity	30,939	29,268
Eliminations [Member]
Consolidating Balance Sheet
Goodwill	(9)	(9)
Investment in subsidiaries	(28,475)	(26,993)
Other assets		(32)
Total assets	(28,484)	(27,034)
Debt		(32)
Total liabilities		(32)
Common stock	(401)	(401)
Additional paid-in capital	(18,717)	(18,657)
Retained earnings	(9,205)	(8,951)
Accumulated other comprehensive income (loss)	(161)	1,007
Total shareholders’ equity	(28,484)	(27,002)
Total liabilities and shareholders’ equity	$ (28,484)	$ (27,034)