Schedule of Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total assets	$ 1,360,259	$ 1,301,146
Goodwill	262,376	262,594	$ 262,813
Hub [Member]
Segment Reporting Information [Line Items]
Goodwill	232,987	233,205	$ 233,424
Operating Segments [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Total assets	1,178,110	1,127,042
Goodwill	232,987	233,205
Operating Segments [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Total assets	191,374	181,514
Goodwill	29,389	29,389
Intersegment Elims [Member]
Segment Reporting Information [Line Items]
Total assets	$ (9,225)	$ (7,410)