Restructuring plan - Additional information (Detail) (USD $)			3 Months Ended		3 Months Ended			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Restructuring Charges Member	Jun. 30, 2014 Restructuring Charges Member	Sep. 30, 2014 Restructuring Charges Member Segment, Continuing Operations [Member]	Jun. 30, 2014 Restructuring Charges Member Segment, Continuing Operations [Member]	Sep. 30, 2013 Restructuring Charges Member Segment, Continuing Operations [Member]	Sep. 30, 2014 Restructuring Charges Member Segment, Continuing Operations [Member]	Sep. 30, 2013 Restructuring Charges Member Segment, Continuing Operations [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring Charges					$ 8,290,000		$ 0	$ 12,864,000	$ 0
Entity Number Of Employees	218	365
Restructuring Reserve			9,425,000	3,481,000
Estimate Of Restructuring Charges To Be Incurred			41,000,000			54,000,000
Estimate Of Severance Retention And Other Payments To Be Incurred			22,000,000			32,000,000
Estimate Of Operational Set Up Cost And Lease Cancellations To Be Incurred			$ 19,000,000			$ 22,000,000