Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities
Net Income	$ 1,045	$ 591	$ 634
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	55	48	52
Realized investment gains, net	(148)	(124)	(70)
Share-based compensation	26	23	20
Interest credited to contract holders'	48	48	44
Deferred income tax expense	(444)	38	16
Changes in:
Investment income receivable	0	(5)	(6)
Premiums and reinsurance receivable	77	(113)	(48)
Deferred policy acquisition costs	(36)	(26)	(18)
Other assets	(43)	34	(39)
Loss and loss expense reserves	188	367	233
Life policy and investment contract reserves	96	102	101
Unearned premiums	97	106	119
Other liabilities	24	61	55
Current income tax receivable/payable	67	(35)	(18)
Net cash provided by operating activities	1,052	1,115	1,075
Cash Flows From Investing Activities
Sale of fixed maturities	23	15	43
Call or maturity of fixed maturities	1,172	1,511	1,199
Sale of equity securities	523	465	342
Purchase of fixed maturities	(1,723)	(1,994)	(1,722)
Purchase of equity securities	(513)	(439)	(493)
Investment in finance receivables	(32)	(17)	(14)
Collection of finance receivables	23	30	30
Investment in buildings and equipment	(16)	(13)	(10)
Change in other invested assets, net	(15)	(14)	1
Net cash used in investing activities	(558)	(456)	(624)
Cash Flows From Financing Activities
Payment of cash dividends to shareholders	(400)	(306)	(366)
Shares acquired - share repurchase authorization	(92)	(39)	(53)
Changes in note payable	4	(15)	(14)
Proceeds from stock options exercised	13	21	24
Contract holders' funds deposited	79	95	83
Contract holders' funds withdrawn	(164)	(155)	(148)
Excess tax benefits on share-based compensation	0	5	4
Other	(54)	(32)	(28)
Net cash used in financing activities	(614)	(426)	(498)
Net change in cash and cash equivalents	(120)	233	(47)
Cash and cash equivalents at beginning of year	777	544	591
Cash and cash equivalents at end of year	657	777	544
Supplemental Disclosures of Cash Flow Information
Interest paid	52	52	52
Income taxes paid	60	213	245
Noncash Activities
Conversion of securities	5	4	3
Equipment acquired under capital lease obligations	14	20	20
Cashless exercise of stock options	7	13	16
Other assets and other liabilities	$ 75	$ 53	$ 27