Employee Pension Benefits - Schedule of Net Periodic Pension Benefit and Related Income Statement Line Item (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit	$ 1,364	$ 1,194	$ 2,726	$ 2,389
Cost of Educational Services [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit	877	787	1,762	1,562
Student Services and Administrative Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit	$ 487	$ 407	$ 964	$ 827