Benefit Plans (Fair Value of Plan Assets) (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		$ 455,000,000	$ 402,000,000	$ 379,000,000
Foreign Plan [Member] | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		355,000,000	300,000,000
Foreign Plan [Member] | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		90,000,000	90,000,000
Foreign Plan [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		10,000,000	12,000,000
Foreign Plan [Member] | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		20,000,000	71,000,000
Foreign Plan [Member] | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		20,000,000	71,000,000
Foreign Plan [Member] | Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Mutual funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		1,000,000	4,000,000
Foreign Plan [Member] | Private equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Private equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Private equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		1,000,000	4,000,000
Foreign Plan [Member] | Government debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		11,000,000	10,000,000
Foreign Plan [Member] | Government debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		11,000,000	10,000,000
Foreign Plan [Member] | Government debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Government debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	[1]	413,000,000	305,000,000
Foreign Plan [Member] | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		323,000,000	215,000,000
Foreign Plan [Member] | Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		90,000,000	90,000,000
Foreign Plan [Member] | Mutual funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		2,000,000	3,000,000
Foreign Plan [Member] | Real estate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		2,000,000	3,000,000
Foreign Plan [Member] | Participant loans
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	[2]	0	2,000,000
Foreign Plan [Member] | Participant loans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Participant loans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Participant loans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	2,000,000
Foreign Plan [Member] | Other assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		8,000,000	7,000,000
Foreign Plan [Member] | Other assets | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		1,000,000	4,000,000
Foreign Plan [Member] | Other assets | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
Foreign Plan [Member] | Other assets | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		7,000,000	3,000,000
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		1,127,000,000	1,044,000,000	$ 1,021,000,000
UNITED STATES | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		1,091,000,000	1,011,000,000
UNITED STATES | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		36,000,000	33,000,000
UNITED STATES | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		359,000,000	532,000,000
UNITED STATES | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		359,000,000	532,000,000
UNITED STATES | Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Mutual funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Government debt securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		135,000,000	86,000,000
UNITED STATES | Government debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		135,000,000	86,000,000
UNITED STATES | Government debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Government debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	[3]	593,000,000	393,000,000
UNITED STATES | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		593,000,000	393,000,000
UNITED STATES | Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Mutual funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		36,000,000	33,000,000
UNITED STATES | Real estate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		0	0
UNITED STATES | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		36,000,000	33,000,000
UNITED STATES | Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan assets		$ 0	$ 0

[1] Mutual funds categorized as debt securities consist of mutual funds for which debt securities are the primary underlying investment

[2] Loans to participants are stated at cost, which approximates fair value

[3] Mutual funds categorized as debt securities consist of mutual funds for which debt securities are the primary underlying investment