Cumulative Effect of Changes Made to Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 30, 2017
ASSETS
Trade accounts receivable	$ 688,961	$ 641,043	$ 631,164
Other current assets, net	29,553	13,925	14,394
Liabilities
Accounts payable	311,768	293,769	285,132
Equity
Retained earnings	1,719,475	1,611,931	1,611,158
Calculated under Revenue Guidance in Effect before Topic 606
ASSETS
Trade accounts receivable	674,781		631,164
Other current assets, net	30,163		14,394
Liabilities
Accounts payable	299,406		285,132
Equity
Retained earnings	1,718,267		$ 1,611,158
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
ASSETS
Trade accounts receivable	14,180	9,879
Other current assets, net	(610)	(469)
Liabilities
Accounts payable	12,362	8,637
Equity
Retained earnings	$ 1,208	$ 773

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Amount of current assets classified as other.

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The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowances established for the purpose of reducing such receivables to an amount that approximates their net realizable value.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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