Fair Value Measurements Investment Fair Value (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Mortgage-backed securities: [Abstract]
Investments		$ 15,351	$ 14,480
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	334
Investment Segment [Member]
Mortgage-backed securities: [Abstract]
Investments		14,553	13,941
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	334
Investment Segment [Member] | Recurring measurement [Member]
Mortgage-backed securities: [Abstract]
Investments		14,553	13,941
Derivative contracts, at fair value(1)	[1]	214	3
Assets, Fair Value Disclosure		14,767	13,944
Marketable Securities, Equity Securities [Abstract]
Derivative contracts, at fair value(2)	[2]	33	627
Financial and Nonfinancial Liabilities, Fair Value Disclosure		827	961
Investment Segment [Member] | Recurring measurement [Member] | Level 1 [Member]
Mortgage-backed securities: [Abstract]
Investments		14,324	13,639
Derivative contracts, at fair value(1)	[1]	0	0
Assets, Fair Value Disclosure		14,324	13,639
Marketable Securities, Equity Securities [Abstract]
Derivative contracts, at fair value(2)	[2]	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		794	334
Investment Segment [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Mortgage-backed securities: [Abstract]
Investments		174	227
Derivative contracts, at fair value(1)	[1]	214	3
Assets, Fair Value Disclosure		388	230
Marketable Securities, Equity Securities [Abstract]
Derivative contracts, at fair value(2)	[2]	33	627
Financial and Nonfinancial Liabilities, Fair Value Disclosure		33	627
Investment Segment [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Mortgage-backed securities: [Abstract]
Investments		55	75
Derivative contracts, at fair value(1)	[1]	0	0
Assets, Fair Value Disclosure		55	75
Marketable Securities, Equity Securities [Abstract]
Derivative contracts, at fair value(2)	[2]	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0	0
Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		14,324	13,639
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	334
Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		14,324	13,639
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	334
Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		72	129
Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17	54
Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		55	75
Basic Materials [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		563	0
Basic Materials [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		563	0
Basic Materials [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Basic Materials [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Communications [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		407	2,846
Communications [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		407	2,846
Communications [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Communications [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Consumer, non-cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		3,684	2,308
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	0
Consumer, non-cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		3,684	2,308
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		794	0
Consumer, non-cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Consumer, non-cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Consumer, cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		115	436
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	334
Consumer, cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		115	436
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	334
Consumer, cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Consumer, cyclical [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Marketable Securities, Equity Securities [Abstract]
Securities sold, not yet purchased, at fair value		0	0
Consumer, cyclical [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		55	75
Consumer, cyclical [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Consumer, cyclical [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Consumer, cyclical [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		55	75
Diversified [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17	23
Diversified [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17	23
Diversified [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Diversified [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Energy sector [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		1,461	1,895
Energy sector [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		1,461	1,895
Energy sector [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Energy sector [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Energy sector [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	19
Energy sector [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Energy sector [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	19
Energy sector [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		2,094	417
Financial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		2,094	417
Financial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		4	7
Financial [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		4	7
Financial [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Collateralized Mortgage Backed Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		157	173
Financial [Member] | Investment Segment [Member] | Collateralized Mortgage Backed Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Financial [Member] | Investment Segment [Member] | Collateralized Mortgage Backed Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		157	173
Financial [Member] | Investment Segment [Member] | Collateralized Mortgage Backed Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Sovereign Debt [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		13	0
Sovereign Debt [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Sovereign Debt [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		13	0
Sovereign Debt [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Funds [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Funds [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Funds [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Funds [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Industrial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		188	79
Industrial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		188	79
Industrial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Industrial [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Technology [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		5,795	5,635
Technology [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		5,795	5,635
Technology [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Technology [Member] | Investment Segment [Member] | Equity securities | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Utilities [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	28
Utilities [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Utilities [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	28
Utilities [Member] | Investment Segment [Member] | Corporate Debt Securities [Member] | Recurring measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		$ 0	$ 0

[1] Included in other assets in our consolidated balance sheets.

[2] Included in accrued expenses and other liabilities in our consolidated balance sheets.