FINANCIAL INFORMATION FOR SUBSIDIARY GUARANTORS AND NON-GUARANTORS - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Sep. 30, 2017	Apr. 01, 2017	Dec. 15, 2016
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES		$ (482.8)	$ (489.0)
INVESTING ACTIVITIES
Proceeds from sale of long-lived assets		0.2	4.8
Post-closing working capital payment related to sale of International Business		(35.3)	0.0
Investments in property, plant and equipment		(33.1)	(32.8)
Investments in loans receivable		(7.7)	0.0
Net (investments in) distributions from unconsolidated affiliates		0.0	(0.2)
Investments in acquired businesses, net of cash acquired		(144.2)	(77.9)
Investing cash flows from (to) affiliates		0.0	0.0
Net cash provided by (used in) investing activities		(220.1)	(106.1)
FINANCING ACTIVITIES
Borrowings under revolving and bank lines of credit and term loans		1,172.6	944.6
Repayments under revolving and bank lines of credit and term loans		(243.4)	(395.0)
Proceeds from issuance of 5.250% Senior Notes		0.0	250.0
Financing and issuance fees		0.0	(3.9)
Dividends paid		(60.3)	(59.9)
Distribution paid by Aerogrow to noncontrolling interest		0.0	(8.1)
Purchase of Common Shares		(256.8)	(99.2)
Payments on seller notes		(3.0)	(13.2)
Excess tax benefits from share-based payment arrangements	$ 3.2	0.0	4.0
Cash received from the exercise of stock options		3.8	1.7
Financing cash flows from (to) affiliates		0.0
Net cash provided by financing activities		612.9	621.0
Effect of exchange rate changes on cash		2.5	(1.7)
Net increase (decrease) in cash and cash equivalents		(87.5)	24.2
Cash and cash equivalents at beginning of period		120.5	28.6
Cash and cash equivalents at end of period	55.4	33.0	55.4
Cash and cash equivalents at beginning of period excluding cash classified within assets held for sale	55.4	120.5	28.6	$ 33.0	$ 120.5	$ 55.4
Cash and cash equivalents at beginning of period classified within assets held for sale		0.0	21.5
Cash and cash equivalents at beginning of period		120.5	50.1
Cash and cash equivalents at end of period	74.3	33.0	74.3
Return of investment from affiliates		0.0	0.0
Senior Notes | Senior Notes – 5.250%
FINANCING ACTIVITIES
Interest rate of debt				5.25%	5.25%	5.25%	5.25%
Reportable Legal Entities | Parent
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES		9.5	(8.2)
INVESTING ACTIVITIES
Proceeds from sale of long-lived assets		0.0	0.0
Post-closing working capital payment related to sale of International Business		0.0
Investments in property, plant and equipment		0.0	0.0
Investments in loans receivable		0.0
Net (investments in) distributions from unconsolidated affiliates			0.0
Investments in acquired businesses, net of cash acquired		0.0	0.0
Investing cash flows from (to) affiliates		(250.2)	(436.1)
Net cash provided by (used in) investing activities		303.8	(84.6)
FINANCING ACTIVITIES
Borrowings under revolving and bank lines of credit and term loans		0.0	0.0
Repayments under revolving and bank lines of credit and term loans		0.0	0.0
Proceeds from issuance of 5.250% Senior Notes			250.0
Financing and issuance fees			(3.8)
Dividends paid		(60.3)	(59.9)
Distribution paid by Aerogrow to noncontrolling interest			0.0
Purchase of Common Shares		(256.8)	(99.2)
Payments on seller notes		0.0	0.0
Excess tax benefits from share-based payment arrangements			4.0
Cash received from the exercise of stock options		3.8	1.7
Financing cash flows from (to) affiliates		0.0	0.0
Net cash provided by financing activities		(313.3)	92.8
Effect of exchange rate changes on cash		0.0	0.0
Net increase (decrease) in cash and cash equivalents		0.0	0.0
Cash and cash equivalents at beginning of period		0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0	0.0
Cash and cash equivalents at beginning of period excluding cash classified within assets held for sale	0.0	0.0	0.0	$ 0.0	$ 0.0	$ 0.0
Cash and cash equivalents at beginning of period classified within assets held for sale			0.0
Cash and cash equivalents at beginning of period			0.0
Cash and cash equivalents at end of period	0.0		0.0
Return of investment from affiliates		554.0	351.5
Reportable Legal Entities | Subsidiary Guarantors
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES		(503.5)	(386.6)
INVESTING ACTIVITIES
Proceeds from sale of long-lived assets		0.2	4.8
Post-closing working capital payment related to sale of International Business		(35.3)
Investments in property, plant and equipment		(29.8)	(27.8)
Investments in loans receivable		(7.4)
Net (investments in) distributions from unconsolidated affiliates			0.0
Investments in acquired businesses, net of cash acquired		(40.5)	(1.5)
Investing cash flows from (to) affiliates		(70.2)	(276.9)
Net cash provided by (used in) investing activities		(183.0)	(269.0)
FINANCING ACTIVITIES
Borrowings under revolving and bank lines of credit and term loans		1,032.9	806.2
Repayments under revolving and bank lines of credit and term loans		(154.8)	(232.3)
Proceeds from issuance of 5.250% Senior Notes			0.0
Financing and issuance fees			(0.1)
Dividends paid		(554.0)	(351.5)
Distribution paid by Aerogrow to noncontrolling interest			0.0
Purchase of Common Shares		0.0	0.0
Payments on seller notes		0.0	0.0
Excess tax benefits from share-based payment arrangements			0.0
Cash received from the exercise of stock options		0.0	0.0
Financing cash flows from (to) affiliates		330.2	436.1
Net cash provided by financing activities		654.3	658.4
Effect of exchange rate changes on cash		0.0	0.0
Net increase (decrease) in cash and cash equivalents		(32.2)	2.8
Cash and cash equivalents at beginning of period		39.8	2.7
Cash and cash equivalents at end of period	5.5	7.6	5.5
Cash and cash equivalents at beginning of period excluding cash classified within assets held for sale	5.5	39.8	2.7	7.6	39.8	5.5
Cash and cash equivalents at beginning of period classified within assets held for sale			0.0
Cash and cash equivalents at beginning of period			2.7
Cash and cash equivalents at end of period	5.5		5.5
Return of investment from affiliates		0.0	32.4
Reportable Legal Entities | Non-Guarantors
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES		25.2	(94.2)
INVESTING ACTIVITIES
Proceeds from sale of long-lived assets		0.0	0.0
Post-closing working capital payment related to sale of International Business		0.0
Investments in property, plant and equipment		(3.3)	(5.0)
Investments in loans receivable		(0.3)
Net (investments in) distributions from unconsolidated affiliates			(0.2)
Investments in acquired businesses, net of cash acquired		(103.7)	(76.4)
Investing cash flows from (to) affiliates		(80.0)	0.0
Net cash provided by (used in) investing activities		(187.3)	(81.6)
FINANCING ACTIVITIES
Borrowings under revolving and bank lines of credit and term loans		139.7	138.4
Repayments under revolving and bank lines of credit and term loans		(88.6)	(162.7)
Proceeds from issuance of 5.250% Senior Notes			0.0
Financing and issuance fees			0.0
Dividends paid		(14.0)	0.0
Distribution paid by Aerogrow to noncontrolling interest			(40.5)
Purchase of Common Shares		0.0	0.0
Payments on seller notes		(3.0)	(13.2)
Excess tax benefits from share-based payment arrangements			0.0
Cash received from the exercise of stock options		0.0	0.0
Financing cash flows from (to) affiliates		70.2	276.9
Net cash provided by financing activities		104.3	198.9
Effect of exchange rate changes on cash		2.5	(1.7)
Net increase (decrease) in cash and cash equivalents		(55.3)	21.4
Cash and cash equivalents at beginning of period		80.7	25.9
Cash and cash equivalents at end of period	49.9	25.4	49.9
Cash and cash equivalents at beginning of period excluding cash classified within assets held for sale	49.9	80.7	25.9	25.4	80.7	49.9
Cash and cash equivalents at beginning of period classified within assets held for sale			21.5
Cash and cash equivalents at beginning of period			47.4
Cash and cash equivalents at end of period	68.8		68.8
Return of investment from affiliates		0.0	0.0
Eliminations/ Consolidations
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES		(14.0)	0.0
INVESTING ACTIVITIES
Proceeds from sale of long-lived assets		0.0	0.0
Post-closing working capital payment related to sale of International Business		0.0
Investments in property, plant and equipment		0.0	0.0
Investments in loans receivable		0.0
Net (investments in) distributions from unconsolidated affiliates			0.0
Investments in acquired businesses, net of cash acquired		0.0	0.0
Investing cash flows from (to) affiliates		400.4	713.0
Net cash provided by (used in) investing activities		(153.6)	329.1
FINANCING ACTIVITIES
Borrowings under revolving and bank lines of credit and term loans		0.0	0.0
Repayments under revolving and bank lines of credit and term loans		0.0	0.0
Proceeds from issuance of 5.250% Senior Notes			0.0
Financing and issuance fees			0.0
Dividends paid		568.0	351.5
Distribution paid by Aerogrow to noncontrolling interest			32.4
Purchase of Common Shares		0.0	0.0
Payments on seller notes		0.0	0.0
Excess tax benefits from share-based payment arrangements			0.0
Cash received from the exercise of stock options		0.0	0.0
Financing cash flows from (to) affiliates		(400.4)	(713.0)
Net cash provided by financing activities		167.6	(329.1)
Effect of exchange rate changes on cash		0.0	0.0
Net increase (decrease) in cash and cash equivalents		0.0	0.0
Cash and cash equivalents at beginning of period		0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0	0.0
Cash and cash equivalents at beginning of period excluding cash classified within assets held for sale	0.0	0.0	0.0	$ 0.0	$ 0.0	$ 0.0
Cash and cash equivalents at beginning of period classified within assets held for sale			0.0
Cash and cash equivalents at beginning of period			0.0
Cash and cash equivalents at end of period	$ 0.0		0.0
Return of investment from affiliates		$ (554.0)	$ (383.9)