Pension and Other Postretirement Benefits - Additional Information (Detail)	12 Months Ended					12 Months Ended		0 Months Ended	12 Months Ended			12 Months Ended					12 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($) Employees	Dec. 31, 2014 GBP (£)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Minimum [Member]	Dec. 31, 2014 Minimum [Member] Multi-Employer Plan [Member] Location	Dec. 31, 2014 Maximum [Member]	May 01, 2014 Other Postretirement Benefits [Member] USD ($)	Dec. 31, 2014 Other Postretirement Benefits [Member] USD ($) Customer	Dec. 31, 2013 Other Postretirement Benefits [Member] USD ($)	Dec. 31, 2012 Other Postretirement Benefits [Member] USD ($)	Dec. 31, 2014 Foreign Pension Benefits [Member] USD ($)	Dec. 31, 2013 Foreign Pension Benefits [Member] USD ($)	Dec. 31, 2012 Foreign Pension Benefits [Member] USD ($)	Dec. 31, 2014 Foreign Pension Benefits [Member] GBP (£)	Dec. 31, 2013 Foreign Pension Benefits [Member] GBP (£)	Dec. 31, 2014 Nonqualified Defined Benefit Pension Plan [Member] USD ($)	Dec. 31, 2013 Nonqualified Defined Benefit Pension Plan [Member] USD ($)	Dec. 31, 2014 U.S. Pension Benefits [Member] USD ($)	Dec. 31, 2013 U.S. Pension Benefits [Member] USD ($)	Dec. 31, 2012 U.S. Pension Benefits [Member] USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Total of lump sum payments	$ 9,304,000								$ 0	$ 0		$ 0	$ 0						$ 9,304,000	$ 0
Minimum contributions required																			0
Voluntary contributions made			5,000,000						589,000	597,000		1,849,000	1,764,000	1,786,000					40,000	5,008,000
Minimum contributions expected in 2015																	0
Estimated benefit payments, in 2015									795,000			1,622,000					74,000		9,019,000
Estimated benefit payments, in 2016									785,000			1,529,000					95,000		9,413,000
Estimated benefit payments, in 2017									788,000			2,144,000					119,000		9,885,000
Estimated benefit payments, in 2018									801,000			1,638,000					418,000		10,264,000
Estimated benefit payments, in 2019									802,000			2,661,000					425,000		10,640,000
Estimated benefit payments, in 2020-2024									4,402,000			14,407,000					2,212,000		58,457,000
Fair value of plan assets	157,048,000								0	0	0	50,533,000	48,536,000	41,875,000	32,437,000	29,315,000			157,048,000	164,085,000	140,218,000
Accumulated benefit obligations												70,523,000	60,830,000		45,268,000	36,740,000	4,294,000	2,794,000	186,870,000	167,723,000
Contributions to defined contribution pension plan		1,123,000										407,000	316,000	311,000
Employer contribution expected in 2015												1,750,000
Contributions to the defined contribution pension plan expected in 2015												412,000
Defined benefit plan contribution made to trusts																	0
Fair market value included in other noncurrent assets																	4,280,000	4,092,000
Number of employer locations contributed to the plan						1,750
Number of employees participate in the plan	275,000	275,000
Multiemployer plan number of employees description	Approximately 275,000	Approximately 275,000
Total amount of assets collected	10,500,000,000
Percentage of funded status in excess	100.00%	100.00%
Participation of corporation's employees in the plan	Less than 100	Less than 100
Corporation's contributions	233,000		230,000	241,000
Percentage of employers contributions	5.00%	5.00%
Contributions expected in 2015	267,000
Number of subsidiary having postretirement health care benefits									1
Service period to avail existing pension plan	15 years	15 years
Reduction in plan liability								8,914,000	(8,914,000)	0		0	0						163,000	681,000
Maximum maturity period of fixed income investments	10 years	10 years
Investments in diversified portfolio	Invests primarily in a diversified portfolio of fixed-income securities of varying maturities or in commingled funds which invest in a diversified portfolio of fixed-income securities of varying maturities.	Invests primarily in a diversified portfolio of fixed-income securities of varying maturities or in commingled funds which invest in a diversified portfolio of fixed-income securities of varying maturities.
Target allocation	Generate a minimum annual inflation adjusted return of 5% and outperform a traditional 70/30 equities/bond portfolio.	Generate a minimum annual inflation adjusted return of 5% and outperform a traditional 70/30 equities/bond portfolio.
Defined benefit plan actuarial gain loss percentage					10.00%		10.00%
High-quality fixed-income investments maturity	10 years	10 years
Change in discounts rates increased plan benefit obligations and reduced the funded status of the plans	(39,000,000)								(13,739,000)	(20,129,000)		(19,990,000)	(12,294,000)						(48,351,000)	(17,521,000)
Increasing projected and accumulated benefit obligations and reducing the funded status of the plans	9,000,000
Assumed health care cost trend rate for 2015	6.00%	6.00%
Percentage decrease in other postretirement benefits in 2018									4.75%
Year related to decrease in health care cost trend rate									2018
Percentage point increase or decrease in the assumed health care cost trend rate									1.00%
One percent effect on postretirement benefit obligation									40,000
One percent effect on annual benefit expense									$ 100,000