Consolidating Financial Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 310	$ 267	$ 291	$ 248	$ 259	$ 274	$ 263	$ 232	$ 1,116	$ 1,029	$ 948
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									37	35	32
Pension, health and life insurance contributions									(42)	(32)	(37)
Pension, health and life insurance benefits expense									28	30	46
Deferred income taxes									(15)	1	(9)
Share-based compensation									16	8	5
Excess tax benefits from share-based arrangements									(4)	(2)	(1)
Changes in operating assets and liabilities:
Accounts and other receivables									1	5	12
Inventories										4	(26)
Accounts payable and accrued liabilities									(33)	(46)	56
Settlement costs									91	78	8
Income taxes									(6)	(34)
Other current assets									(10)	(2)
Other assets									4	17	(4)
Other											7
Net cash provided by (used in) operating activities									1,183	1,091	1,037
Cash flows from investing activities:
Additions to plant and equipment									(56)	(40)	(51)
Net cash provided by (used in) investing activities									(56)	(40)	(51)
Cash flows from financing activities:
Shares repurchased									(1,586)	(716)	(910)
Proceeds from issuance of long-term debt									750	1,000	750
Dividends paid									(723)	(645)	(631)
Debt issuance costs									(9)	(13)	(5)
Proceeds from exercise of stock options									8		2
Excess tax benefits from share-based arrangements									4	2	1
Net cash provided by (used in) financing activities									(1,556)	(372)	(793)
Change in cash and cash equivalents									(429)	679	193
Cash and cash equivalents, beginning of year				2,063				1,384	2,063	1,384	1,191
Cash and cash equivalents, end of year	1,634				2,063				1,634	2,063	1,384
Parent [Member]
Cash flows from operating activities:
Net income									1,116	1,029	948
Adjustments to reconcile net income to net cash provided by operating activities:
Equity income from subsidiaries									(1,115)	(1,029)	(949)
Deferred income taxes										(5)
Share-based compensation										1
Changes in operating assets and liabilities:
Accounts and other receivables									(1)
Accounts payable and accrued liabilities									12	(16)	18
Income taxes										(1)
Return on investment in subsidiaries									1,730	1,398	1,635
Net cash provided by (used in) operating activities									1,742	1,377	1,652
Cash flows from investing activities:
Return of capital									252	17
Net cash provided by (used in) investing activities									252	17
Cash flows from financing activities:
Shares repurchased									(1,586)	(716)	(910)
Proceeds from issuance of long-term debt									387
Dividends paid									(723)	(645)	(631)
Net cash provided by (used in) financing activities									(1,922)	(1,361)	(1,541)
Change in cash and cash equivalents									72	33	111
Cash and cash equivalents, beginning of year				163				130	163	130	19
Cash and cash equivalents, end of year	235				163				235	163	130
Issuer [Member]
Cash flows from operating activities:
Net income									1,115	1,029	949
Adjustments to reconcile net income to net cash provided by operating activities:
Equity income from subsidiaries									(659)	(592)	(388)
Depreciation and amortization									37	35	32
Pension, health and life insurance contributions									(42)	(32)	(37)
Pension, health and life insurance benefits expense									28	30	46
Deferred income taxes									(16)	7	(10)
Share-based compensation									16	7	5
Excess tax benefits from share-based arrangements									(4)	(2)	(1)
Changes in operating assets and liabilities:
Accounts and other receivables									(873)	5	16
Inventories										4	(26)
Accounts payable and accrued liabilities									(37)	(14)	39
Settlement costs									91	78	8
Income taxes									(2)	(44)
Other current assets									(10)	(2)
Other assets									(170)	2	(4)
Other											13
Return on investment in subsidiaries									1,212	401	350
Net cash provided by (used in) operating activities									686	912	992
Cash flows from investing activities:
Additions to plant and equipment									(56)	(40)	(51)
Return of capital											100
Net cash provided by (used in) investing activities									(56)	(40)	49
Cash flows from financing activities:
Proceeds from issuance of long-term debt									750	1,000	750
Dividends paid									(1,982)	(1,399)	(1,635)
Debt issuance costs									(9)	(13)	(5)
Proceeds from exercise of stock options									8		2
Excess tax benefits from share-based arrangements									4	2	1
Net cash provided by (used in) financing activities									(1,229)	(410)	(887)
Change in cash and cash equivalents									(599)	462	154
Cash and cash equivalents, beginning of year				1,181				719	1,181	719	565
Cash and cash equivalents, end of year	582				1,181				582	1,181	719
All Other Subsidiaries [Member]
Cash flows from operating activities:
Net income									659	592	388
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes									1	(1)	1
Changes in operating assets and liabilities:
Accounts and other receivables									(2)		(4)
Accounts payable and accrued liabilities									869	(16)	(1)
Income taxes									(4)	11
Other assets									(213)	15
Other											(6)
Net cash provided by (used in) operating activities									1,310	601	378
Cash flows from financing activities:
Dividends paid									(1,212)	(417)	(450)
Net cash provided by (used in) financing activities									(1,212)	(417)	(450)
Change in cash and cash equivalents									98	184	(72)
Cash and cash equivalents, beginning of year				719				535	719	535	607
Cash and cash equivalents, end of year	817				719				817	719	535
Total Consolidating Adjustments [Member]
Cash flows from operating activities:
Net income									(1,774)	(1,621)	(1,337)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity income from subsidiaries									1,774	1,621	1,337
Changes in operating assets and liabilities:
Accounts and other receivables									877
Accounts payable and accrued liabilities									(877)
Other assets									387
Return on investment in subsidiaries									(2,942)	(1,799)	(1,985)
Net cash provided by (used in) operating activities									(2,555)	(1,799)	(1,985)
Cash flows from investing activities:
Return of capital									(252)	(17)	(100)
Net cash provided by (used in) investing activities									(252)	(17)	(100)
Cash flows from financing activities:
Proceeds from issuance of long-term debt									(387)
Dividends paid									3,194	1,816	2,085
Net cash provided by (used in) financing activities									2,807	1,816	2,085
Cash and cash equivalents, beginning of year				0				0	0	0	0
Cash and cash equivalents, end of year	$ 0				$ 0				$ 0	$ 0	$ 0