Employee Benefit Plans - Component of Net Periodic Pension Cost (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Jan. 31, 2011	Dec. 31, 2013	Dec. 31, 2013 Chesapeake Pension Plan	Dec. 31, 2012 Chesapeake Pension Plan	Dec. 31, 2011 Chesapeake Pension Plan	Dec. 31, 2013 FPU Pension Plan	Dec. 31, 2012 FPU Pension Plan	Dec. 31, 2011 FPU Pension Plan	Dec. 31, 2013 Chesapeake SERP	Dec. 31, 2012 Chesapeake SERP	Dec. 31, 2011 Chesapeake SERP	Dec. 31, 2013 Chesapeake Postretirement Plan	Dec. 31, 2012 Chesapeake Postretirement Plan	Dec. 31, 2011 Chesapeake Postretirement Plan	Dec. 31, 2013 FPU Medical Plan	Dec. 31, 2012 FPU Medical Plan	Dec. 31, 2011 FPU Medical Plan	Dec. 31, 2013 FPU	Dec. 31, 2012 FPU	Dec. 31, 2011 FPU
Components of net periodic cost:
Service cost												$ 0	$ 0	$ 0	$ 0	$ 1	$ 125
Interest cost			405	458	520	2,367	2,577	2,695	81	90	107	47	55	64	63	79	176
Expected return on assets			(486)	(418)	(424)	(2,866)	(2,627)	(2,783)
Amortization of prior service cost			(1)	(5)	(5)	0	0	0	19	19	19	(77)	(77)	(77)	0	0	0
Actuarial (gain) loss			322	255	156	330	196	0	64	46	38	74	73	67	0	0	55
Net periodic pension cost			240	290	247	(169)	146	(88)	164	155	164	44	51	54	63	80	356
Settlement expense	(436)		0	0	217	0	0	0			219
Curtailment gain		0											0	0	0	(892)	0
Expected Amortization Of Pre Merger Regulatory Asset		0											0	0				8	8	8
Amortization of pre-merger regulatory asset		769	0	0	0	761	761	761	0			0			8
Net periodic postretirement cost			$ 240	$ 290	$ 464	$ 592	$ 907	$ 673	$ 164	$ 155	$ 383	$ 44	$ 51	$ 54	$ 71	$ (804)	$ 364
Assumptions
Discount rate			3.50%	4.25%	5.00%	3.75%	4.50%	5.25%	3.50%	4.25%	5.00%	3.50%	4.25%	5.00%	3.75%	4.50%	5.25%
Expected return on plan assets			6.00%	6.00%	6.00%	7.00%	7.00%	7.00%