Employee Benefit Plans - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, employer contributions	$ 0	$ 0
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Obligations under the supplemental plan	$ 20,500,000		$ 21,400,000