Retirement Plan Benefits - Actual Allocation of the Assets in the Pension Plan (Details)	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	100.00%	100.00%
U.S. large capitalization equities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	29.00%	30.00%
U.S. small capitalization equities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	6.00%	6.00%
International equities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	7.00%	7.00%
U.S. long-duration fixed income
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	55.00%	54.00%
Below Investment Grade Corporate Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation of the Pension Plan assets	3.00%	3.00%