Quarterly Results (Unaudited) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Quarterly Financial Information [Line Items]
Revenues	$ 1,768,830	$ 1,705,105	$ 1,599,141	$ 1,491,645	$ 1,625,859	$ 1,537,966	$ 1,503,224	$ 1,413,208	$ 6,564,721		$ 6,080,257		$ 5,992,215
Net revenues	518,871	513,256	484,714	464,586	478,072	484,902	471,872	448,007	1,981,427	[1]	1,882,853	[1]	1,835,370	[1]
Net earnings	100,740	102,797	91,728	84,195	84,009	92,729	92,663	80,610	379,460		350,011		332,969
Net earnings attributable to shareholders	$ 99,381	$ 102,381	$ 91,302	$ 83,824	$ 83,496	$ 92,400	$ 92,315	$ 80,315	$ 376,888		$ 348,526		$ 333,360
Diluted earnings attributable to shareholders per share	$ 0.51	$ 0.53	$ 0.46	$ 0.42	$ 0.41	$ 0.45	$ 0.45	$ 0.39	$ 1.92		$ 1.68		$ 1.57
Basic earnings attributable to shareholders per share	$ 0.52	$ 0.53	$ 0.46	$ 0.42	$ 0.41	$ 0.45	$ 0.45	$ 0.39	$ 1.92		$ 1.69		$ 1.58

[1] Net revenues are a non-GAAP measure calculated as revenues less directly related operations expenses attributable to the Company's principal services. The Company's management believes that net revenues are a better measure than total revenues when evaluating the Company's operating segment performance since total revenues earned as a freight consolidator include the carriers' charges for carrying the shipment, whereas revenues earned in other capacities include primarily the commissions and fees earned by the Company. Net revenue is one of the Company's primary operational and financial measures and demonstrates the Company's ability to concentrate and leverage purchasing power through effective consolidation of shipments from customers utilizing a variety of transportation carriers and optimal routings.