Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Return on Plan Assets	$ 20	$ 2
Estimated net actuarial loss for the defined benefit pension plan	8
Estimated future employer contributions in next fiscal year	20
Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Return on Plan Assets	$ 7