Employee Benefit Plans - Schedule of Estimated Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Chesapeake Pension Plan
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2017	$ 687	[1]
2018	490	[1]
2019	675	[1]
2020	779	[1]
2021	592	[1]
Years 2022 through 2026	5,278	[1]
FPU Pension Plan
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2017	3,078	[1]
2018	3,207	[1]
2019	3,304	[1]
2020	3,362	[1]
2021	3,536	[1]
Years 2022 through 2026	18,608	[1]
Chesapeake SERP
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2017	151	[2]
2018	150	[2]
2019	149	[2]
2020	385	[2]
2021	146	[2]
Years 2022 through 2026	738	[2]
Chesapeake Postretirement Plan
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2017	97	[2]
2018	96	[2]
2019	85	[2]
2020	82	[2]
2021	81	[2]
Years 2022 through 2026	290	[2]
FPU Medical Plan
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2017	88	[2]
2018	94	[2]
2019	87	[2]
2020	91	[2]
2021	93	[2]
Years 2022 through 2026	$ 404	[2]

[1] The pension plan is funded; therefore, benefit payments are expected to be paid out of the plan assets.

[2] Benefit payments are expected to be paid out of our general funds.