Pension Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net settlement loss	$ 1,700	$ 1,700	$ 2,400
Minimum time period for expected rate of return	10 years
Maximum time period for expected rate of return	20 years
Accrued cost related to pension plans included in other long term liabilities	$ 31,600	34,800
Change in equity as a result of change in deferred net loss	4,500	3,800	100
Change in equity as result of change in deferred net loss taxes	$ 1,500	0	(100)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of qualified earnings credited to the account of the participant of benefit plan	3.00%
Retirement age benefit payable to a terminated vested participant upon retirement	65 years
Retirement age for benefit payments, earliest age allowed contingent of minimum service requirement	55 years
Number of years of service at the time plan was frozen for the eligibility of benefit payable to terminated vested participant at age 55	15 years
Net settlement loss	$ 1,734	1,715	$ 2,356
Expected contribution to defined benefit plan	1,600
Net gain recognized in other comprehensive income	4,500	3,800
Unrecognized actuarial losses included in other comprehensive loss, net of tax	25,000	27,900
Unrecognized actuarial losses included in other comprehensive loss	35,900	$ 40,400
Defined benefit plan amounts that will be amortized from accumulated other comprehensive income loss in next fiscal year	1,000
Non Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for defined benefit plan	$ 15,100