XML 74 R59.htm IDEA: XBRL DOCUMENT v3.8.0.1
Regulatory - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Regulated Operations [Abstract]      
Comprehensive review period 10 years    
Mid-term report period 4 years    
Revenue from Title IV program funds 71.50% 72.30% 74.80%