Guarantor Financial Statements (Condensed Consolidating Cash Flow Statement) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	$ 13.8	$ 47.7
Cash Flows from investing activities:
Capital expenditures	(21.0)	(9.9)
Net cash paid for businesses acquired	(144.8)	(2.6)
Proceeds from the sale of property and equipment	0.1	2.3
Change in restricted cash and marketable securities	0.2	0.1
Other, net	(1.1)	0.1
Net cash used in investing activities	(166.6)	(10.0)
Cash Flows from financing activities:
Proceeds from borrowings	126.6	32.4
Payment of borrowings	(68.1)	(66.9)
Fees paid in connection with debt facilities	0	(1.0)
Net use from equity transactions	(1.6)	0.2
Long-term intercompany advances and loans	0	0
Other, net	0	(0.1)
Net cash provided by (used in) financing activities	56.9	(35.4)
Net change in unrestricted cash and cash equivalents	(95.9)	2.3
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	48.8	60.5
Nortek [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(79.8)	(70.8)
Cash Flows from investing activities:
Capital expenditures	(3.2)	(0.2)
Net cash paid for businesses acquired	(143.9)	(2.6)
Proceeds from the sale of property and equipment	0	0
Change in restricted cash and marketable securities	0	0
Other, net	0	0.1
Net cash used in investing activities	(147.1)	(2.7)
Cash Flows from financing activities:
Proceeds from borrowings	125.0	30.0
Payment of borrowings	(65.3)	(56.8)
Fees paid in connection with debt facilities		(1.0)
Net use from equity transactions	(1.6)	0.2
Long-term intercompany advances and loans	85.9	95.6
Other, net	0	(0.1)
Net cash provided by (used in) financing activities	144.0	67.9
Net change in unrestricted cash and cash equivalents	(82.9)	(5.6)
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	12.0	12.2
Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	97.7	109.7
Cash Flows from investing activities:
Capital expenditures	(12.4)	(7.3)
Net cash paid for businesses acquired	0	0
Proceeds from the sale of property and equipment	0	2.3
Change in restricted cash and marketable securities	0.2	0.1
Other, net	(1.2)	0
Net cash used in investing activities	(13.4)	(4.9)
Cash Flows from financing activities:
Proceeds from borrowings	0	0
Payment of borrowings	(1.3)	(1.1)
Fees paid in connection with debt facilities		0
Net use from equity transactions	0	0
Long-term intercompany advances and loans	(85.9)	(100.6)
Other, net	0	0
Net cash provided by (used in) financing activities	(87.2)	(101.7)
Net change in unrestricted cash and cash equivalents	(2.9)	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	10.2	12.4
Non-Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(4.1)	8.8
Cash Flows from investing activities:
Capital expenditures	(5.4)	(2.4)
Net cash paid for businesses acquired	(0.9)	0
Proceeds from the sale of property and equipment	0.1	0
Change in restricted cash and marketable securities	0	0
Other, net	0.1	0
Net cash used in investing activities	(6.1)	(2.4)
Cash Flows from financing activities:
Proceeds from borrowings	1.6	2.4
Payment of borrowings	(1.5)	(9.0)
Fees paid in connection with debt facilities		0
Net use from equity transactions	0	0
Long-term intercompany advances and loans	0	5.0
Other, net	0	0
Net cash provided by (used in) financing activities	0.1	(1.6)
Net change in unrestricted cash and cash equivalents	(10.1)	4.8
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	$ 26.6	$ 35.9