Annual report pursuant to Section 13 and 15(d)

Quarterly Results of Operations-Unaudited - Quarterly Results of Operations (Parenthetical) (Detail)

v3.8.0.1
Quarterly Results of Operations-Unaudited - Quarterly Results of Operations (Parenthetical) (Detail) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 12 Months Ended
Jan. 31, 2017
Jan. 31, 2018
Jan. 31, 2017
Jul. 31, 2016
Jan. 31, 2018
Jan. 31, 2017
Jan. 31, 2016
Schedule Of Quarterly Financial Information [Line Items]              
Income tax (benefit) provision   $ (14,700)   $ 14,600 $ (12,272) $ 14,631 $ (1,029)
Undistributed earnings of foreign subsidiaries       $ 58,600      
Loss on impairment of long-lived assets $ 500   $ 23,500     $ 23,772 $ 21,464
Impairment charge to write down investment in affiliate     500        
T-Mobile [Member] | Layer3 TV, Inc. [Member]              
Schedule Of Quarterly Financial Information [Line Items]              
Gain on sale of investment   $ 2,600          
Operating Income (Loss) [Member]              
Schedule Of Quarterly Financial Information [Line Items]              
Loss on impairment of long-lived assets     23,700        
New Hampshire [Member]              
Schedule Of Quarterly Financial Information [Line Items]              
Loss on impairment of long-lived assets     $ 200