Benefit Obligations (Schedule of Company Commitments to Fund Benefit Obligations) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Multiemployer Plans, Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions year-to-date	$ 2	[1]
Total expected contributions in current fiscal year	7	[1]
Cash Contributions to Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions year-to-date	5
Total expected contributions in current fiscal year	20
Other Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions year-to-date	5
Total expected contributions in current fiscal year	22
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions year-to-date	1
Total expected contributions in current fiscal year	$ 4

[1] The Company makes contributions based on specified percentages of employee contributions.