Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 29, 2017	Sep. 30, 2016
Current Assets:
Cash and cash equivalents	$ 774,151	$ 655,716
Receivables	2,102,543	2,115,663
Prepaid expenses and other current assets	119,486	93,091
Total current assets	2,996,180	2,864,470
Property, Equipment, and Improvements, net	349,911	319,673
Other Noncurrent Assets:
Goodwill	3,009,826	3,079,628
Intangibles, net	332,920	336,922
Miscellaneous	692,022	759,329
Total other noncurrent assets	4,034,768	4,175,879
Assets	7,380,859	7,360,022
Current Liabilities:
Notes payable	3,071	2,421
Accounts payable	683,605	522,427
Accrued liabilities	939,687	938,378
Billings in excess of costs	299,864	319,460
Total current liabilities	1,926,227	1,782,686
Long-term Debt	235,000	385,330
Other Deferred Liabilities	732,281	861,824
Commitments and Contingencies
Capital stock:
Preferred stock, $1 par value, authorized—1,000,000 shares; issued and outstanding—none
Common stock, $1 par value, authorized—240,000,000 shares; issued and outstanding—120,385,544 shares and 120,950,899 shares as of September 29, 2017 and September 30, 2016, respectively	120,386	120,951
Additional paid-in capital	1,239,782	1,168,272
Retained earnings	3,721,698	3,586,647
Accumulated other comprehensive loss	(653,514)	(610,594)
Total Jacobs stockholders’ equity	4,428,352	4,265,276
Noncontrolling interests	58,999	64,906
Total Group stockholders’ equity	4,487,351	4,330,182
Liabilities and Stockholders' Equity, Total	$ 7,380,859	$ 7,360,022

Capital Stock [Abstract]

No definition available.

Name:	jec_CapitalStockAbstract
Namespace Prefix:	jec_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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).