Defined Contribution Plans, Pension and Other Post-Retirement Benefit Plans - Fair Values of Pension Plan Assets by Asset Category and by Level (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	$ 69,876	$ 71,413
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	551	223
U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,222	4,356
U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	3,961	4,213
International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	7,874	6,490
International growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		2,590
Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,429	2,656
Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	20,528	20,202
Government Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,298	4,540
Corporate Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	17,368	18,186
U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	8,645	7,622
U.K. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		335
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	11,163	14,038
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	551	223
Level 1 | U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,222	4,356
Level 1 | U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	3,961	4,213
Level 1 | International growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		2,590
Level 1 | Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,429	2,656
Level 1 | Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	50,068	49,418
Level 2 | International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	7,874	6,490
Level 2 | International growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		0
Level 2 | Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	20,528	20,202
Level 2 | Government Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,298	4,540
Level 2 | Corporate Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	17,368	18,186
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	8,645	7,957	$ 9,610
Level 3 | U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	$ 8,645	7,622
Level 3 | U.K. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets		$ 335