Guarantor Financial Statements - Condensed Consolidating Cash Flow Statement (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	$ (60.5)	$ 13.8
Cash Flows from investing activities:
Capital expenditures	(18.3)	(21.0)
Net cash paid for businesses acquired	(254.9)	(144.8)
Intercompany dividends	0
Intercompany contributions	0
Investment in joint venture	0
Proceeds from the sale of property and equipment	1.6	0.1
Change in restricted cash and marketable securities	0.3	0.2
Other, net	(1.5)	(1.1)
Net cash used in investing activities	(272.8)	(166.6)
Cash Flows from financing activities:
Proceeds from borrowings	141.5	126.6
Payment of borrowings	(48.1)	(68.1)
Net proceeds from borrowings under the senior secured term loan facility due 2020	349.1	0
Redemption of the senior secured term loan facility due 2017	(93.0)	0
Fees paid in connection with debt facilities	(5.9)	0
Net use from equity transactions	(3.7)	(1.6)
Excess tax benefit on share-based awards	3.8	0
Long-term intercompany advances and loans	0	0
Other, net	0	0
Net cash provided by financing activities	343.7	56.9
Net change in unrestricted cash and cash equivalents	10.4	(95.9)
Unrestricted cash and cash equivalents at the beginning of the period	80.9	144.7
Unrestricted cash and cash equivalents at the end of the period	91.3	48.8
Nortek [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(89.7)	(79.8)
Cash Flows from investing activities:
Capital expenditures	(4.9)	(3.2)
Net cash paid for businesses acquired	(184.5)	(143.9)
Intercompany dividends	0
Intercompany contributions	(0.3)
Investment in joint venture	0
Proceeds from the sale of property and equipment	0	0
Change in restricted cash and marketable securities	0.1	0
Other, net	0	0
Net cash used in investing activities	(189.6)	(147.1)
Cash Flows from financing activities:
Proceeds from borrowings	140.0	125.0
Payment of borrowings	(45.1)	(65.3)
Net proceeds from borrowings under the senior secured term loan facility due 2020	349.1
Redemption of the senior secured term loan facility due 2017	(93.0)
Fees paid in connection with debt facilities	(5.9)
Net use from equity transactions	(3.7)	(1.6)
Excess tax benefit on share-based awards	3.8
Long-term intercompany advances and loans	(51.6)	85.9
Other, net	0	0
Net cash provided by financing activities	293.6	144.0
Net change in unrestricted cash and cash equivalents	14.3	(82.9)
Unrestricted cash and cash equivalents at the beginning of the period	23.2	94.9
Unrestricted cash and cash equivalents at the end of the period	37.5	12.0
Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	17.2	97.7
Cash Flows from investing activities:
Capital expenditures	(11.1)	(12.4)
Net cash paid for businesses acquired	0	0
Intercompany dividends	15.5
Intercompany contributions	0
Investment in joint venture	0
Proceeds from the sale of property and equipment	1.1	0
Change in restricted cash and marketable securities	0.1	0.2
Other, net	(1.5)	(1.2)
Net cash used in investing activities	4.1	(13.4)
Cash Flows from financing activities:
Proceeds from borrowings	0	0
Payment of borrowings	(1.4)	(1.3)
Net proceeds from borrowings under the senior secured term loan facility due 2020	0
Redemption of the senior secured term loan facility due 2017	0
Fees paid in connection with debt facilities	0
Net use from equity transactions	0	0
Excess tax benefit on share-based awards	0
Long-term intercompany advances and loans	(25.8)	(85.9)
Other, net	0	0
Net cash provided by financing activities	(27.2)	(87.2)
Net change in unrestricted cash and cash equivalents	(5.9)	(2.9)
Unrestricted cash and cash equivalents at the beginning of the period	20.0	13.1
Unrestricted cash and cash equivalents at the end of the period	14.1	10.2
Non-Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	12.0	(4.1)
Cash Flows from investing activities:
Capital expenditures	(2.3)	(5.4)
Net cash paid for businesses acquired	(70.4)	(0.9)
Intercompany dividends	(15.5)
Intercompany contributions	0.3
Investment in joint venture	0
Proceeds from the sale of property and equipment	0.5	0.1
Change in restricted cash and marketable securities	0.1	0
Other, net	0	0.1
Net cash used in investing activities	(87.3)	(6.1)
Cash Flows from financing activities:
Proceeds from borrowings	1.5	1.6
Payment of borrowings	(1.6)	(1.5)
Net proceeds from borrowings under the senior secured term loan facility due 2020	0
Redemption of the senior secured term loan facility due 2017	0
Fees paid in connection with debt facilities	0
Net use from equity transactions	0	0
Excess tax benefit on share-based awards	0
Long-term intercompany advances and loans	77.4	0
Other, net	0	0
Net cash provided by financing activities	77.3	0.1
Net change in unrestricted cash and cash equivalents	2.0	(10.1)
Unrestricted cash and cash equivalents at the beginning of the period	37.7	36.7
Unrestricted cash and cash equivalents at the end of the period	$ 39.7	$ 26.6