(Goodwill acquired in business combination by reportable segment) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2014	$ 669,652
Goodwill, Purchase Accounting Adjustments	1,598
Goodwill, Acquired During Period	15,737
Goodwill balance as of September 30, 2015	686,987
TL [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2014	319,051
Goodwill, Purchase Accounting Adjustments	1,598
Goodwill, Acquired During Period	15,737
Goodwill balance as of September 30, 2015	336,386
LTL [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2014	197,312
Goodwill, Purchase Accounting Adjustments	0
Goodwill, Acquired During Period	0
Goodwill balance as of September 30, 2015	197,312
Global Solutions [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2014	153,289
Goodwill, Purchase Accounting Adjustments	0
Goodwill, Acquired During Period	0
Goodwill balance as of September 30, 2015	$ 153,289