Qualified Employee Benefit Plans - The Retirement Plan's Asset Allocation Percentages (Details) - Retirement Plan [Member]	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations, percent	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations, percent	56.00%	62.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations, percent	24.00%	18.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations, percent	20.00%	20.00%