Guarantor Financial Statements (Condensed Consolidating Cash Flow Statement) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	$ 96.0	$ 137.9
Cash Flows from investing activities:
Capital expenditures	(32.9)	(16.1)
Net cash paid for businesses acquired	(146.4)	(2.6)
Investment in joint venture		0
Proceeds from the sale of property and equipment	0.1	2.5
Change in restricted cash and marketable securities	0.2	0.2
Other, net	(1.0)	0.5
Net cash used in investing activities	(180.0)	(15.5)
Cash Flows from financing activities:
Proceeds from borrowings	137.3	33.5
Payment of borrowings	(109.4)	(82.0)
Fees paid in connection with debt facilities	0	(1.3)
Net use from equity transactions	(1.8)	0
Long-term intercompany advances and loans	0	0
Other, net	(0.2)	(0.1)
Net cash provided by (used in) financing activities	25.9	(49.9)
Net change in unrestricted cash and cash equivalents	(58.1)	72.5
Unrestricted cash and cash equivalents at the beginning of the period	144.7	58.2
Unrestricted cash and cash equivalents at the end of the period	86.6	130.7
Nortek [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(100.3)	(86.2)
Cash Flows from investing activities:
Capital expenditures	(4.3)	(0.7)
Net cash paid for businesses acquired	(145.5)	(2.6)
Investment in joint venture		0
Proceeds from the sale of property and equipment	0	0
Change in restricted cash and marketable securities	0.1	0.1
Other, net	0	0.1
Net cash used in investing activities	(149.7)	(3.1)
Cash Flows from financing activities:
Proceeds from borrowings	135.0	30.0
Payment of borrowings	(105.3)	(57.6)
Fees paid in connection with debt facilities		(1.3)
Net use from equity transactions	(1.8)
Long-term intercompany advances and loans	165.7	186.1
Other, net	(0.2)	(0.1)
Net cash provided by (used in) financing activities	193.4	157.1
Net change in unrestricted cash and cash equivalents	(56.6)	67.8
Unrestricted cash and cash equivalents at the beginning of the period	94.9	17.8
Unrestricted cash and cash equivalents at the end of the period	38.3	85.6
Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	194.0	201.6
Cash Flows from investing activities:
Capital expenditures	(20.6)	(11.5)
Net cash paid for businesses acquired	0	0
Investment in joint venture		6.5
Proceeds from the sale of property and equipment	0.1	2.4
Change in restricted cash and marketable securities	0.1	0.1
Other, net	(1.6)	0.2
Net cash used in investing activities	(22.0)	(2.3)
Cash Flows from financing activities:
Proceeds from borrowings	0	0
Payment of borrowings	(1.9)	(1.8)
Fees paid in connection with debt facilities		0
Net use from equity transactions	0
Long-term intercompany advances and loans	(165.7)	(194.4)
Other, net	0	0
Net cash provided by (used in) financing activities	(167.6)	(196.2)
Net change in unrestricted cash and cash equivalents	4.4	3.1
Unrestricted cash and cash equivalents at the beginning of the period	13.1	9.3
Unrestricted cash and cash equivalents at the end of the period	17.5	12.4
Non-Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	2.3	22.5
Cash Flows from investing activities:
Capital expenditures	(8.0)	(3.9)
Net cash paid for businesses acquired	(0.9)	0
Investment in joint venture		(6.5)
Proceeds from the sale of property and equipment	0	0.1
Change in restricted cash and marketable securities	0	0
Other, net	0.6	0.2
Net cash used in investing activities	(8.3)	(10.1)
Cash Flows from financing activities:
Proceeds from borrowings	2.3	3.5
Payment of borrowings	(2.2)	(22.6)
Fees paid in connection with debt facilities		0
Net use from equity transactions	0
Long-term intercompany advances and loans	0	8.3
Other, net	0	0
Net cash provided by (used in) financing activities	0.1	(10.8)
Net change in unrestricted cash and cash equivalents	(5.9)	1.6
Unrestricted cash and cash equivalents at the beginning of the period	36.7	31.1
Unrestricted cash and cash equivalents at the end of the period	$ 30.8	$ 32.7