Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Payables and Accruals [Abstract]    
Accounts payable $ 22,826 $ 32,783
Accrued salaries and bonuses 80,541 231,390
Accrued payroll taxes and benefits 40,379 49,858
Accrued professional liabilities 20,432 19,718
Accrued contingent consideration 18,264 17,010
Other accrued expenses 29,848 29,899
Accounts payable and accrued expenses, total $ 212,290 $ 380,658