Financial Instruments (Offsetting of Financial Assets and Financial Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Derivative Assets [Abstract]
Derivatives - Gross Amounts of Recognized Assets	$ 573		$ 232
Derivatives - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Derivatives - Net Presented in the Consolidated Balance Sheets	573		232
Derivatives - Financial Instruments	(1)	[1]	(2)	[1]
Derivatives - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	(180)		(35)
Derivatives - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Received	(269)		(52)
Derivatives - Net Assets Exposed	123		143
Offsetting Securities Purchased under Agreements to Resell and Securities Borrowed [Abstract]
Reverse repurchase agreements - Gross Amounts of Recognized Assets	2,924		1,370
Reverse repurchase agreements - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Reverse repurchase agreements - Net Presented in the Consolidated Balance Sheets	2,924	[2]	1,370	[2]
Reverse repurchase agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0		0
Reverse repurchase agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	0		0
Reverse repurchase agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Received	(2,924)		(1,370)
Reverse repurchase agreements - Net Assets Exposed	0		0
Offsetting Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed [Abstract]
Total - Gross Amounts of Recognized Assets	3,497		1,602
Total - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Total - Net Presented in the Consolidated Balance Sheets	3,497		1,602
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	(1)		(2)
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Received	(180)		(35)
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Received	(3,193)		(1,422)
Total - Net Assets Exposed	123		143
Offsetting Derivative Liabilities [Abstract]
Derivatives - Gross Amounts of Recognized Liabilities	3		4
Derivatives - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Derivatives - Net Presented in the Consolidated Balance Sheets	3		4
Derivatives - Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	(1)	[3]	(2)	[3]
Derivatives - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Derivatives - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Pledged	0		0
Derivatives - Net Liabilities	2		2
Offsetting Securities Loaned [Abstract]
Securities lending agreements - Gross Amounts of Recognized Liabilities	3,402		1,374
Securities lending agreements - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Securities lending agreements - Net Presented in the Consolidated Balance Sheets	3,402		1,374
Securities lending agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	0		0
Securities lending agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Securities lending agreements - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Pledged	(3,347)		(1,357)
Securities lending agreements - Net Liabilities	55		17
Offsetting Derivative Liability, Securities Sold under Agreements to Resell, Securities Loaned [Abstract]
Total - Gross Amounts of Recognized Liabilities	3,405		1,378
Total - Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Total - Net Presented in the Consolidated Balance Sheets	3,405		1,378
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Financial Instruments	(1)		(2)
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Cash Collateral Pledged	0		0
Total - Gross Amounts Not Offset in the Consolidated Balance Sheets - Non-Cash Collateral Pledged	(3,347)		(1,357)
Total - Net Liabilities	57		19
Cash and cash equivalents
Offsetting Securities Purchased under Agreements to Resell and Securities Borrowed [Abstract]
Reverse repurchase agreements - Gross Amounts of Recognized Assets	2,099		1,270
Receivable under reverse repurchase agreements
Offsetting Securities Purchased under Agreements to Resell and Securities Borrowed [Abstract]
Reverse repurchase agreements - Gross Amounts of Recognized Assets	$ 825		$ 100

[1] The balances at December 31, 2013 and September 30, 2014 were related to derivative liabilities which are allowed to be net settled against derivative assets in accordance with our master netting agreements.

[2] The balances at December 31, 2013 and September 30, 2014 included $1,270 million and $2,099 million recorded in cash and cash equivalents, respectively, and $100 million and $825 million recorded in receivable under reverse repurchase agreements, respectively.

[3] The balances at December 31, 2013 and September 30, 2014 were related to derivative assets which are allowed to be net settled against derivative liabilities in accordance with our master netting agreements.