Restructuring - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 employee
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative	$ 13,672,000	$ 0	$ 32,473,000
Restructuring liabilities	6,056,000	0	10,887,000
2014 Initiative
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative	13,672,000
Number of employees	217
2011 Initiative
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative			32,473,000	32,500,000
Number of employees				491
Restructuring liabilities		$ 0