Employee Benefit Plans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date			Jun. 30, 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	4,000,000		4,000,000		4,400,000
Defined Benefit Plan, Net Periodic Benefit Cost	12,000	34,000	23,000	66,000
Contribution to pension plan	130,000		221,000
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	(125,000)	(43,000)	(251,000)	(87,000)
Contribution to pension plan	419,000		630,000
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	41,000	79,000	83,000
Contribution to pension plan	22,000		45,000
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	10,000	11,000	20,000	21,000
Contribution to pension plan	22,000		45,000
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	16,000	16,000	33,000	32,000
Contribution to pension plan	89,000		144,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			$ 245,000