Schedule of Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 1,643,270	$ 1,670,941
Goodwill	348,161	348,661
Operating Segments [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Total assets	1,444,239	1,470,792
Goodwill	318,772	319,272
Operating Segments [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Total assets	205,070	210,088
Goodwill	29,389	29,389
Intersegment Elims [Member]
Segment Reporting Information [Line Items]
Total assets	$ (6,039)	$ (9,939)