Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Consolidating Statement of Cash Flows
Net income	$ 664	$ 812	$ 1,355	$ 1,645
Net adjustments to reconcile net income to net cash provided by (used in) operating activities			(62)	(770)
Net cash provided by operating activities			1,293	875
Proceeds from maturities of fixed maturities			3,773	5,314
Proceeds from sales of investments, fixed maturities			739	1,226
Proceeds from sales of investments, equity securities			38	28
Proceeds from sales of investments, real estate investments			69	10
Proceeds from sales of investments, other investments			343	354
Purchases of investments, fixed maturities			(5,705)	(6,239)
Purchases of investments, equity securities			(26)	(22)
Purchases of investments, real estate investments			(20)	(69)
Purchases of investments, other investments			(290)	(275)
Net (purchases) sales of short-term securities			681	433
Securities transactions in course of settlement			461	183
Other investing activities			(154)	(178)
Net cash provided by (used in) investing activities			(91)	765
Treasury stock acquired - share repurchase authorization			(1,100)	(1,400)
Treasury stock acquired - net employee share-based compensation			(59)	(72)
Dividends paid to shareholders			(375)	(369)
Payment of debt			(400)
Issuance of debt			491
Issuance of common stock - employee share options			129	117
Excess tax benefits from share-based payment arrangements				31
Net cash used in financing activities			(1,314)	(1,693)
Effect of exchange rate changes on cash			(3)	(4)
Net decrease in cash			(115)	(57)
Cash at beginning of year			380	374
Cash at end of period	265	317	265	317
Income taxes paid (received)			467	597
Interest paid			180	183
TPC [Member]
Consolidating Statement of Cash Flows
Net income	502	628	1,027	1,260
Net adjustments to reconcile net income to net cash provided by (used in) operating activities			(17)	(410)
Net cash provided by operating activities			1,010	850
Proceeds from maturities of fixed maturities			2,728	3,604
Proceeds from sales of investments, fixed maturities			385	710
Proceeds from sales of investments, equity securities			10	11
Proceeds from sales of investments, other investments			233	244
Purchases of investments, fixed maturities			(3,588)	(4,352)
Purchases of investments, equity securities			(5)	(2)
Purchases of investments, other investments			(221)	(222)
Net (purchases) sales of short-term securities			193	327
Securities transactions in course of settlement			325	190
Other investing activities			(151)	(175)
Net cash provided by (used in) investing activities			(91)	335
Dividends paid to parent company			(1,025)	(1,222)
Net cash used in financing activities			(1,025)	(1,222)
Effect of exchange rate changes on cash			2
Net decrease in cash			(104)	(37)
Cash at beginning of year			225	221
Cash at end of period	121	184	121	184
Income taxes paid (received)			398	534
Interest paid			24	24
Other Subsidiaries [Member]
Consolidating Statement of Cash Flows
Net income	203	245	408	500
Net adjustments to reconcile net income to net cash provided by (used in) operating activities			(222)	(520)
Net cash provided by operating activities			186	(20)
Proceeds from maturities of fixed maturities			1,040	1,707
Proceeds from sales of investments, fixed maturities			352	516
Proceeds from sales of investments, equity securities			28	17
Proceeds from sales of investments, real estate investments			69	10
Proceeds from sales of investments, other investments			110	110
Purchases of investments, fixed maturities			(2,108)	(1,869)
Purchases of investments, equity securities			(19)	(19)
Purchases of investments, real estate investments			(20)	(69)
Purchases of investments, other investments			(69)	(53)
Net (purchases) sales of short-term securities			639	224
Securities transactions in course of settlement			137	(7)
Other investing activities			(3)	(3)
Net cash provided by (used in) investing activities			156	564
Dividends paid to parent company			(349)	(560)
Net cash used in financing activities			(349)	(560)
Effect of exchange rate changes on cash			(5)	(4)
Net decrease in cash			(12)	(20)
Cash at beginning of year			153	151
Cash at end of period	141	131	141	131
Income taxes paid (received)			142	197
TRV [Member]
Consolidating Statement of Cash Flows
Net income	664	812	1,355	1,645
Net adjustments to reconcile net income to net cash provided by (used in) operating activities			116	182
Net cash provided by operating activities			1,471	1,827
Proceeds from maturities of fixed maturities			5	3
Proceeds from sales of investments, fixed maturities			2
Purchases of investments, fixed maturities			(9)	(18)
Purchases of investments, equity securities			(2)	(1)
Net (purchases) sales of short-term securities			(151)	(118)
Securities transactions in course of settlement			(1)
Net cash provided by (used in) investing activities			(156)	(134)
Treasury stock acquired - share repurchase authorization			(1,100)	(1,400)
Treasury stock acquired - net employee share-based compensation			(59)	(72)
Dividends paid to shareholders			(375)	(369)
Payment of debt			(400)
Issuance of debt			491
Issuance of common stock - employee share options			129	117
Excess tax benefits from share-based payment arrangements				31
Net cash used in financing activities			(1,314)	(1,693)
Net decrease in cash			1
Cash at beginning of year			2	2
Cash at end of period	3	2	3	2
Income taxes paid (received)			(73)	(134)
Interest paid			156	159
Eliminations [Member]
Consolidating Statement of Cash Flows
Net income	$ (705)	$ (873)	(1,435)	(1,760)
Net adjustments to reconcile net income to net cash provided by (used in) operating activities			61	(22)
Net cash provided by operating activities			(1,374)	(1,782)
Dividends paid to parent company			1,374	1,782
Net cash used in financing activities			$ 1,374	$ 1,782