Guarantor Financial Statements (Condensed Consolidating Cash Flow Statement) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	$ (14.5)	$ 44.3
Cash Flows from investing activities:
Capital expenditures	(9.8)	(4.5)
Net cash paid for businesses acquired	(0.9)	0
Proceeds from the sale of property and equipment	0	1.5
Change in restricted cash and marketable securities	0.1	0.1
Other, net	(0.8)	(0.1)
Net cash used in investing activities	(11.4)	(3.0)
Cash Flows from financing activities:
Increase in borrowings	85.8	1.6
Payment of borrowings	(1.6)	(28.7)
Net use from equity transactions	(1.6)	0
Long-term intercompany advances and loans	0	0
Net cash provided by (used in) financing activities	82.6	(27.1)
Net change in unrestricted cash and cash equivalents	56.7	14.2
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	201.4	72.4
Nortek [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(18.3)	(16.5)
Cash Flows from investing activities:
Capital expenditures	(1.5)	0
Net cash paid for businesses acquired	0
Proceeds from the sale of property and equipment		0
Change in restricted cash and marketable securities	0	0.1
Other, net	0	0
Net cash used in investing activities	(1.5)	0.1
Cash Flows from financing activities:
Increase in borrowings	85.0	0
Payment of borrowings	(0.1)	(25.9)
Net use from equity transactions	(1.6)
Long-term intercompany advances and loans	7.6	59.1
Net cash provided by (used in) financing activities	90.9	33.2
Net change in unrestricted cash and cash equivalents	71.1	16.8
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	166.0	34.6
Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	6.8	59.8
Cash Flows from investing activities:
Capital expenditures	(4.9)	(3.1)
Net cash paid for businesses acquired	0
Proceeds from the sale of property and equipment		1.5
Change in restricted cash and marketable securities	0.1	0
Other, net	(0.9)	(0.1)
Net cash used in investing activities	(5.7)	(1.7)
Cash Flows from financing activities:
Increase in borrowings	0	0
Payment of borrowings	(0.7)	(0.6)
Net use from equity transactions	0
Long-term intercompany advances and loans	(7.6)	(64.1)
Net cash provided by (used in) financing activities	(8.3)	(64.7)
Net change in unrestricted cash and cash equivalents	(7.2)	(6.6)
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	5.9	2.7
Non-Guarantor Subsidiaries [Member]
Cash Flows from operating activities:
Net cash (used in) provided by operating activities	(3.0)	1.0
Cash Flows from investing activities:
Capital expenditures	(3.4)	(1.4)
Net cash paid for businesses acquired	(0.9)
Proceeds from the sale of property and equipment		0
Change in restricted cash and marketable securities	0	0
Other, net	0.1	0
Net cash used in investing activities	(4.2)	(1.4)
Cash Flows from financing activities:
Increase in borrowings	0.8	1.6
Payment of borrowings	(0.8)	(2.2)
Net use from equity transactions	0
Long-term intercompany advances and loans	0	5.0
Net cash provided by (used in) financing activities	0	4.4
Net change in unrestricted cash and cash equivalents	(7.2)	4.0
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	$ 29.5	$ 35.1