Employee Benefit Plans, Fair Value of Assets Qualified Plans (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		$ 2,428	$ 2,097
Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		1,078	1,115
Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		1,350	982
Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
US Companies [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[1]	571	562
US Companies [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[1]	571	562
US Companies [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[1]	0	0
US Companies [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[1]	0	0
International Companies [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		188	164
International Companies [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		187	164
International Companies [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		1	0
International Companies [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Preferred Stock [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		4	3
Preferred Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		4	3
Preferred Stock [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Preferred Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
International Growth [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		118	90
International Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		118	90
International Growth [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
International Growth [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Index Funds [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[2]	85	230
Index Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[2]	85	230
Index Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[2]	0	0
Index Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[2]	$ 0	$ 0
Index Fund - Equity Securities [Member]
Employee Benefit Plans (Textual)
Defined benefit plan, actual plan asset allocations		70.00%	50.00%
Index Fund - Debt Securities [Member]
Employee Benefit Plans (Textual)
Defined benefit plan, actual plan asset allocations		30.00%	50.00%
Corporate Debt Instruments [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		$ 272	$ 280
Corporate Debt Instruments [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Corporate Debt Instruments [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		272	280
Corporate Debt Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
US Treasury Securities [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		45	52
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		45	52
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Other Government Securities [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		144	158
Other Government Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Other Government Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		144	158
Other Government Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Common Collective Trusts [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[3]	621	434
Common Collective Trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[3]	0	0
Common Collective Trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[3]	621	434
Common Collective Trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets	[3]	$ 0	$ 0
Common Collective Trusts - Equity Securities [Member]
Employee Benefit Plans (Textual)
Defined benefit plan, actual plan asset allocations		80.00%	90.00%
Common Collective Trusts - Debt Securities [Member]
Employee Benefit Plans (Textual)
Defined benefit plan, actual plan asset allocations		20.00%	10.00%
Pooled Separate Accounts [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		$ 192
Pooled Separate Accounts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0
Pooled Separate Accounts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		192
Pooled Separate Accounts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0
Private Funds [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		101	$ 76
Private Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Private Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		101	76
Private Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Insurance Contract [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		18	18
Insurance Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Insurance Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		18	18
Insurance Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Interest and Dividends Receivable [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		5	5
Interest and Dividends Receivable [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		5	5
Interest and Dividends Receivable [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Interest and Dividends Receivable [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Cash and Cash Equivalents [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		86	72
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		85	56
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		1	16
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Securities Transactions Receivable (Payable), Net [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		(22)	(47)
Securities Transactions Receivable (Payable), Net [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		(22)	(47)
Securities Transactions Receivable (Payable), Net [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		0	0
Securities Transactions Receivable (Payable), Net [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Values of Qualified Pension Plan Assets
Fair value of qualified pension plan assets		$ 0	$ 0
Equity Securities [Member]
Employee Benefit Plans (Textual)
Percentage of equity securities in target allocations for plan assets		70.00%
Debt Securities [Member]
Employee Benefit Plans (Textual)
Percentage of equity securities in target allocations for plan assets		30.00%

[1] Equity securities are held in a wide range of industrial sectors, including consumer goods, information technology, healthcare, industrials, and financial services.

[2] This class includes primarily investments in approximately 70 percent equities and 30 percent bonds

[3] This class includes primarily investments in approximately 80 percent equities and 20 percent bonds as of December 31, 2017. As of December 31, 2016, the class included primarily investments in approximately 90 percent equities and 10 percent bonds.