Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Other Commitments [Line Items]
Severance Payment Under Agreement Description	Certain of the agreements also provide for a severance payment of one to three times annual salary and one half to three times average annual bonus if such an agreement is terminated without good cause by the employer or for good reason by the employee.
Employees under contract terminated by employer without good cause or change in control	$ 41.6
Employees under contract terminated by employer without good cause or in absence of change in control	$ 19.2
Minimum [Member]
Other Commitments [Line Items]
Period for providing minimum compensation salary and continuation of certain benefits to executives under employment agreements	6 months
Severance payment as a percentage of annual salary	100.00%
Severance payment as a percentage of annual bonus	50.00%
Maximum [Member]
Other Commitments [Line Items]
Period for providing minimum compensation salary and continuation of certain benefits to executives under employment agreements	3 years
Severance payment as a percentage of annual salary	300.00%
Severance payment as a percentage of annual bonus	300.00%