Property and Equipment - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Depreciation expense for continuing operations	$ 67.4	$ 73.3	$ 70.8
Depreciation expense for discontinued operations	4.4	6.1	7.6
Leased Facilities And Equipment [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges	2.7
Leased Facilities [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges	2.7	1.0
Property and Equipment [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges	8.0	29.5
Teach Out Schools [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges	$ 2.6	$ 28.5