Retirement Plans and Postretirement Medical Benefits (Level 3 Gains and Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
United States
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	$ 158,095	$ 158,021
Realized gains	15,325	11,471
Unrealized gains	227	8,085
Net purchases, sales and settlements	(25,909)	(19,482)
Balance at	147,738	158,095
United States | Mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	2,102	2,634
Realized gains	10	12
Unrealized gains	28	59
Net purchases, sales and settlements	(548)	(603)
Balance at	1,592	2,102
United States | Private equity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	81,246	87,470
Realized gains	14,288	11,174
Unrealized gains	(6,844)	1,886
Net purchases, sales and settlements	(25,113)	(19,284)
Balance at	63,577	81,246
United States | Real estate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	74,747	67,917
Realized gains	1,027	285
Unrealized gains	7,043	6,140
Net purchases, sales and settlements	(248)	405
Balance at	82,569	74,747
Foreign
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	0
Unrealized gains	(1,804)
Net purchases, sales and settlements	61,494
Balance at	59,690	0
Foreign | Real estate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	0
Unrealized gains	(1,685)
Net purchases, sales and settlements	40,862
Balance at	39,177	0
Foreign | Diversified growth funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	0
Unrealized gains	(119)
Net purchases, sales and settlements	20,632
Balance at	$ 20,513	$ 0