Summary of Basis Used to Measure Defined Benefit Plans Assets at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 101,916	$ 104,291
U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	26,787	31,831
U.S. Small / Mid Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	7,950	8,783
International, Equity
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	14,797	25,591
U.S. Intermediate
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	14,906	18,715
U.S. Short Duration
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	8,817	8,954
U.S. High Yield
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	5,270	1,581
International, Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	20,776	5,812
Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	284	331
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	2,329	2,693
Level 1
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	81,013	103,960
Level 1 | U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	26,787	31,831
Level 1 | U.S. Small / Mid Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	7,950	8,783
Level 1 | International, Equity
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	8,275	25,591
Level 1 | U.S. Intermediate
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	14,906	18,715
Level 1 | U.S. Short Duration
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	8,817	8,954
Level 1 | U.S. High Yield
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	5,270	1,581
Level 1 | International, Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,679	5,812
Level 1 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	2,329	2,693
Level 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	20,903	331
Level 2 | U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | U.S. Small / Mid Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | International, Equity
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,522	0
Level 2 | U.S. Intermediate
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | U.S. Short Duration
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | U.S. High Yield
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | International, Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	14,097	0
Level 2 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	284	331
Level 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | U.S. Small / Mid Cap
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | International, Equity
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | U.S. Intermediate
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | U.S. Short Duration
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | U.S. High Yield
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | International, Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 0	$ 0