Employee Pension Benefits - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost included in net periodic pension benefit	$ 0
Expected significant contributions to pension plans	0
Net periodic pension benefit	1,362,000	$ 1,195,000
Cost of Educational Services [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit	885,000
Student Services and Administrative Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit	477,000
ESI Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions to pension plans	0	0
ESI Excess Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions to pension plans	$ 0	$ 0