Employee Benefit Plans - Schedule of Assets by Investment Type (Detail)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Chesapeake Pension Plan
Asset Category
Percentage of assets by investment type	100.00%	100.00%	100.00%
Chesapeake Pension Plan | Investments in equity securities
Asset Category
Percentage of assets by investment type	54.40%	52.07%	51.75%
Chesapeake Pension Plan | Debt securities
Asset Category
Percentage of assets by investment type	36.54%	38.00%	37.88%
Chesapeake Pension Plan | Other
Asset Category
Percentage of assets by investment type	9.06%	9.93%	10.37%
FPU Pension Plan
Asset Category
Percentage of assets by investment type	100.00%	100.00%	100.00%
FPU Pension Plan | Investments in equity securities
Asset Category
Percentage of assets by investment type	55.02%	52.81%	51.98%
FPU Pension Plan | Debt securities
Asset Category
Percentage of assets by investment type	36.54%	38.04%	38.05%
FPU Pension Plan | Other
Asset Category
Percentage of assets by investment type	8.44%	9.15%	9.97%