Cumulative Effect of Changes Made to Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 30, 2017
ASSETS
Trade accounts receivable	$ 631,828	$ 641,043	$ 631,164
Other current assets, net	9,373	13,925	14,394
Liabilities
Accounts payable	282,480	293,769	285,132
Equity
Retained earnings	1,663,140	1,611,931	1,611,158
Calculated under Revenue Guidance in Effect before Topic 606
ASSETS
Trade accounts receivable	619,754		631,164
Other current assets, net			14,394
Liabilities
Accounts payable	271,956		285,132
Equity
Retained earnings	1,662,134		$ 1,611,158
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
ASSETS
Trade accounts receivable	12,074	9,879
Other current assets, net		(469)
Liabilities
Accounts payable	10,524	8,637
Equity
Retained earnings	$ 1,006	$ 773