Pension Plans and Defined Contribution Plan - Schedule of Fair Values of Pension Plan Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 142,088	$ 162,977
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	874	655
Domestic Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,204	10,464
Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,563	7,089
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,962	17,155
Master Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,368
Equity Securities [Member] | U.S. Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27,779	23,072
Equity Securities [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,960	18,211
Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,504	13,127
Equity Securities [Member] | U.S. Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9,974	7,256
Fixed Income [Member] | U.S. Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,778	59,517
Fixed Income [Member] | U.S. Inflation Protected Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	403	1,236
Fixed Income [Member] | High Yield Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	912	2,295
Fixed Income [Member] | International Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	807	2,900
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125,126	145,822
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	874	655
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Domestic Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,204	10,464
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,563	7,089
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Master Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,368
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Equity Securities [Member] | U.S. Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27,779	23,072
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Equity Securities [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,960	18,211
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,504	13,127
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Equity Securities [Member] | U.S. Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9,974	7,256
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Fixed Income [Member] | U.S. Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,778	59,517
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Fixed Income [Member] | U.S. Inflation Protected Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	403	1,236
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Fixed Income [Member] | High Yield Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	912	2,295
Quoted Prices in Active Markets for Identical Assets or Liabilities Level 1 [Member] | Fixed Income [Member] | International Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	807	2,900
Significant Other Observable Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,962	17,155
Significant Other Observable Inputs Level 2 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 16,962	$ 17,155