Benefit Plans (Fair Value of Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
U.S. Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	$ 1,061	$ 941	$ 883
U.S. Defined Benefit Plans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	1,011	720
U.S. Defined Benefit Plans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	50	221
U.S. Defined Benefit Plans | Common stock
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	46
U.S. Defined Benefit Plans | Common stock | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	46
U.S. Defined Benefit Plans | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	467	303
U.S. Defined Benefit Plans | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	467	303
U.S. Defined Benefit Plans | Government debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	67	32
U.S. Defined Benefit Plans | Government debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	67	24
U.S. Defined Benefit Plans | Government debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	8
U.S. Defined Benefit Plans | Corporate debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	159
U.S. Defined Benefit Plans | Corporate debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0
U.S. Defined Benefit Plans | Corporate debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	159
U.S. Defined Benefit Plans | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	473	251
U.S. Defined Benefit Plans | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	473	251
U.S. Defined Benefit Plans | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	26	23
U.S. Defined Benefit Plans | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	26	23
U.S. Defined Benefit Plans | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	4	56
U.S. Defined Benefit Plans | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	4	56
U.S. Defined Benefit Plans | Other investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	24	71
U.S. Defined Benefit Plans | Other investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	0	40
U.S. Defined Benefit Plans | Other investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	24	31
Foreign Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	3,272	3,605	4,712
Foreign Defined Benefit Plans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	523	546
Foreign Defined Benefit Plans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	2,353	2,529
Foreign Defined Benefit Plans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	396	530	635
Foreign Defined Benefit Plans | Common stock
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	21	23
Foreign Defined Benefit Plans | Common stock | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	21	23
Foreign Defined Benefit Plans | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	274	322
Foreign Defined Benefit Plans | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	274	322
Foreign Defined Benefit Plans | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	237	370
Foreign Defined Benefit Plans | Private equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	237	370
Foreign Defined Benefit Plans | Certificates of deposit
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	3	2
Foreign Defined Benefit Plans | Certificates of deposit | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	3	2
Foreign Defined Benefit Plans | Unsecured debentures
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	10	13
Foreign Defined Benefit Plans | Unsecured debentures | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	10	13
Foreign Defined Benefit Plans | Government debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	110	107
Foreign Defined Benefit Plans | Government debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	12	12
Foreign Defined Benefit Plans | Government debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	98	95
Foreign Defined Benefit Plans | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	2,451	2,584
Foreign Defined Benefit Plans | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	215	174
Foreign Defined Benefit Plans | Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	2,236	2,410
Foreign Defined Benefit Plans | Other debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	6	9
Foreign Defined Benefit Plans | Other debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	6	9
Foreign Defined Benefit Plans | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	103	100
Foreign Defined Benefit Plans | Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	103	100
Foreign Defined Benefit Plans | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	1	15
Foreign Defined Benefit Plans | Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	1	15
Foreign Defined Benefit Plans | Participant loans
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	52	60
Foreign Defined Benefit Plans | Participant loans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	52	60
Foreign Defined Benefit Plans | Other assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	4
Foreign Defined Benefit Plans | Other assets | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	$ 4