Employee Benefit Plans - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date	Mar. 31, 2014
Expected pension and postretirement benefit costs	$ 578,000
Expected amortization of pre merger regulatory asset	769,000
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Unamortized balance of regulatory asset	4,200,000		4,400,000
Defined Benefit Plan, Net Periodic Benefit Cost	11,000	33,000
Contribution to pension plan	91,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	520,000
Consolidated [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	191,000
FPU Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	(126,000)	(44,000)
Contribution to pension plan	211,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	1,677,000
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	40,000	42,000
Contribution to pension plan	22,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	88,000
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	11,000	11,000
Contribution to pension plan	23,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	95,000
FPU Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	17,000	16,000
Contribution to pension plan	55,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	$ 245,000