Basis Of Presentation and Significant Accounting Policies	6 Months Ended
Apr. 01, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis Of Presentation And Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The accompanying Condensed Consolidated Financial Statements included herein have been prepared by Plexus Corp. and its subsidiaries (together “Plexus” or the “Company”) without audit and pursuant to the rules and regulations of the United States (“U.S.”) Securities and Exchange Commission (“SEC”). In the opinion of the Company, the accompanying Condensed Consolidated Financial Statements reflect all adjustments, which include normal recurring adjustments necessary for the fair statement of the consolidated financial position of the Company as of April 1, 2017 and October 1, 2016, and the results of operations for the three and six months ended April 1, 2017 and April 2, 2016, and the cash flows for the same six month periods. The Company’s fiscal year ends on the Saturday closest to September 30. The Company also uses a “4-4-5” weekly accounting system for the interim periods in each quarter. Each quarter, therefore, ends on a Saturday at the end of the 4-4-5 period. Periodically, an additional week must be added to the fiscal year to re-align with the Saturday closest to September 30. All fiscal quarters presented herein included 13 weeks. Certain information and footnote disclosures, normally included in financial statements prepared in accordance with generally accepted accounting principles, have been condensed or omitted pursuant to the SEC’s rules and regulations dealing with interim financial statements. However, the Company believes that the disclosures made in the Condensed Consolidated Financial Statements included herein are adequate to make the information presented not misleading. It is suggested that these Condensed Consolidated Financial Statements be read in conjunction with the Consolidated Financial Statements and notes thereto included in the Company’s 2016 Annual Report on Form 10-K. The Company’s reportable segments consist of the “Americas” (“AMER”), “Asia-Pacific” (“APAC”) and “Europe, Middle East, and Africa” (“EMEA”) segments. Refer to Note 9, "Reportable Segments," for further details on reportable segments. Cash and Cash Equivalents and Restricted Cash Cash and cash equivalents include short-term, highly liquid investments and are classified as Level 1 in the fair value hierarchy described below. Restricted cash represents cash received from customers to settle invoices sold under master accounts receivable purchase agreements and is therefore contractually required to be set aside. The restrictions will lapse when the cash is remitted to the purchaser. This is also classified as Level 1 in the fair value hierarchy described below. Noncash Supplemental Executive Retirement Plan Transaction In March 2017, the Company changed trustee for its supplemental executive retirement plan. The change resulted in a settlement and re-investment of $10.3 million, with no actual cash received or distributed by the Company. Fair Value of Financial Instruments The Company holds financial instruments consisting of cash and cash equivalents, restricted cash, accounts receivable, certain deferred compensation assets held under trust arrangements, accounts payable, debt, derivatives, and capital lease obligations. The carrying values of cash and cash equivalents, restricted cash, accounts receivable, accounts payable, and capital lease obligations as reported in the Condensed Consolidated Financial Statements approximate fair value. Derivatives and certain deferred compensation assets held under trust arrangements are recorded at fair value. Accounts receivable are reflected at net realizable value based on anticipated losses due to potentially uncollectible balances. Anticipated losses are based on management’s analysis of historical losses and changes in customers’ credit status. The fair value of the Company’s long-term debt was $174.0 million and $176.4 million as of April 1, 2017 and October 1, 2016, respectively. The carrying value of the Company’s long-term debt was $175.0 million as of both April 1, 2017 and October 1, 2016. The Company uses quoted market prices when available or discounted cash flows to calculate the fair value of its debt. If measured at fair value in the financial statements, long-term debt (including the current portion) would be classified as Level 2 in the fair value hierarchy described below. Refer to Note 4, "Derivatives and Fair Value Measurements," for further details on derivatives. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (or exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The accounting guidance establishes a fair value hierarchy based on three levels of inputs that may be used to measure fair value. The input levels are: Level 1: Quoted (observable) market prices in active markets for identical assets or liabilities. Level 2: Inputs other than Level 1 that are observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability. Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the asset or liability.

Basis of Presentation and Significant Accounting Policies

Basis of Presentation

The accompanying Condensed Consolidated Financial Statements included herein have been prepared by Plexus Corp. and its subsidiaries (together “Plexus” or the “Company”) without audit and pursuant to the rules and regulations of the United States (“U.S.”) Securities and Exchange Commission (“SEC”). In the opinion of the Company, the accompanying Condensed Consolidated Financial Statements reflect all adjustments, which include normal recurring adjustments necessary for the fair statement of the consolidated financial position of the Company as of April 1, 2017 and October 1, 2016, and the results of operations for the three and six months ended April 1, 2017 and April 2, 2016, and the cash flows for the same six month periods.

The Company’s fiscal year ends on the Saturday closest to September 30. The Company also uses a “4-4-5” weekly accounting system for the interim periods in each quarter. Each quarter, therefore, ends on a Saturday at the end of the 4-4-5 period. Periodically, an additional week must be added to the fiscal year to re-align with the Saturday closest to September 30. All fiscal quarters presented herein included 13 weeks.

Certain information and footnote disclosures, normally included in financial statements prepared in accordance with generally accepted accounting principles, have been condensed or omitted pursuant to the SEC’s rules and regulations dealing with interim financial statements. However, the Company believes that the disclosures made in the Condensed Consolidated Financial Statements included herein are adequate to make the information presented not misleading. It is suggested that these Condensed Consolidated Financial Statements be read in conjunction with the Consolidated Financial Statements and notes thereto included in the Company’s 2016 Annual Report on Form 10-K.

The Company’s reportable segments consist of the “Americas” (“AMER”), “Asia-Pacific” (“APAC”) and “Europe, Middle East, and Africa” (“EMEA”) segments. Refer to Note 9, "Reportable Segments," for further details on reportable segments.

Cash and Cash Equivalents and Restricted Cash

Cash and cash equivalents include short-term, highly liquid investments and are classified as Level 1 in the fair value hierarchy described below. Restricted cash represents cash received from customers to settle invoices sold under master accounts receivable purchase agreements and is therefore contractually required to be set aside. The restrictions will lapse when the cash is remitted to the purchaser. This is also classified as Level 1 in the fair value hierarchy described below.

Noncash Supplemental Executive Retirement Plan Transaction

In March 2017, the Company changed trustee for its supplemental executive retirement plan. The change resulted in a settlement and re-investment of $10.3 million, with no actual cash received or distributed by the Company.

Fair Value of Financial Instruments

The Company holds financial instruments consisting of cash and cash equivalents, restricted cash, accounts receivable, certain deferred compensation assets held under trust arrangements, accounts payable, debt, derivatives, and capital lease obligations. The carrying values of cash and cash equivalents, restricted cash, accounts receivable, accounts payable, and capital lease obligations as reported in the Condensed Consolidated Financial Statements approximate fair value. Derivatives and certain deferred compensation assets held under trust arrangements are recorded at fair value. Accounts receivable are reflected at net realizable value based on anticipated losses due to potentially uncollectible balances. Anticipated losses are based on management’s analysis of historical losses and changes in customers’ credit status. The fair value of the Company’s long-term debt was $174.0 million and $176.4 million as of April 1, 2017 and October 1, 2016, respectively. The carrying value of the Company’s long-term debt was $175.0 million as of both April 1, 2017 and October 1, 2016. The Company uses quoted market prices when available or discounted cash flows to calculate the fair value of its debt. If measured at fair value in the financial statements, long-term debt (including the current portion) would be classified as Level 2 in the fair value hierarchy described below. Refer to Note 4, "Derivatives and Fair Value Measurements," for further details on derivatives.

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (or exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The accounting guidance establishes a fair value hierarchy based on three levels of inputs that may be used to measure fair value. The input levels are:

Level 1: Quoted (observable) market prices in active markets for identical assets or liabilities.

Level 2: Inputs other than Level 1 that are observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability.

Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the asset or liability.