Special Charges - Additional Information (Detail) (USD $)	3 Months Ended						12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012 Location Employee
Special Charges [Line Items]
Special charges	$ 1,628,000	$ 5,347,000	$ 9,364,000	$ 27,568,000	$ 10,419,000	$ 427,000	$ 16,339,000	$ 38,414,000	$ 29,557,000
Post-employment severance costs							6,100,000
Restructuring charge, non-cash							700,000
Non cash special charges								14,100,000	5,000,000
Number of employees terminated									116
Number of office locations									9
Total cash outflow associated with special charges, amount paid							65,200,000	65,200,000	65,200,000
Cash outflow associated with special charges, amount paid							46,600,000
Cash outflow associated with special charges, amount expected to be paid in 2015							6,900,000
Cash outflow associated with special charges, amount expected to be paid in 2016							3,200,000
Cash outflow associated with special charges, amount expected to be paid in 2017							3,100,000
Cash outflow associated with special charges, amount expected to be paid in 2018							2,600,000
Cash outflow associated with special charges, amount expected to be paid from 2019 to 2025							2,800,000
Lease Termination
Special Charges [Line Items]
Special charges							7,900,000
Closure of West Palm Beach Executive Office
Special Charges [Line Items]
Special charges							$ 2,300,000