Pension and Other Postretirement Employee Benefit Plans - Investment Strategy and Asset Allocation (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Pension and other postretirement employee benefit plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Investments sponsored or managed by affiliates	$ 3.2	$ 3.7
Non-U.S. pension and other postretirement employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Investments sponsored or managed by affiliates	$ 1.2	$ 1.4
United States equity securities | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	45.00%
International equity securities | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	40.00%
Debt securities | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	80.00%
Hedge funds | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	5.00%
Real estate | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	10.00%
Real assets | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	10.00%
Private equity | Defined benefit pension plans, U.S.
Defined Benefit Plan Disclosure [Line Items]
Target allocation, minimum	0.00%
Target allocation, maximum	20.00%