Employee Benefit Plans - Employee Benefit Plans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date	Mar. 31, 2014
Amortization of prior service cost	$ (14)
Amortization of net loss	66
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	107	102
Expected return on plan assets	(133)	(126)
Amortization of prior service cost	0	0
Amortization of net loss	37	57
Net periodic cost (benefit)	11	33
Total periodic cost	11	33
FPU Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	647	594
Expected return on plan assets	(773)	(719)
Amortization of net loss	0	81
Net periodic cost (benefit)	(126)	(44)
Amortization of pre-merger regulatory asset	190	190
Total periodic cost	64	146
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	23	21
Amortization of prior service cost	5	5
Amortization of net loss	12	16
Net periodic cost (benefit)	40	42
Total periodic cost	40	42
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	13	12
Amortization of prior service cost	(19)	(19)
Amortization of net loss	17	18
Net periodic cost (benefit)	11	11
Total periodic cost	11	11
FPU Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	17	16
Amortization of net loss	0	0
Net periodic cost (benefit)	17	16
Amortization of pre-merger regulatory asset	2	2
Total periodic cost	$ 19	$ 18