Segment Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Segment Reporting Information [Line Items]
Net sales, excluding intercompany	$ 288.1	$ 283.1	$ 545.5	$ 528.2
2013	1.7	1.9	3.3	3.3
Operating income	25.3	24.3	39.3	31.2
Depreciation and amortization	13.8	15.0	28.5	29.8
Restructuring	2.7	0.4	2.8	1.1
2013	10.8	8.7	18.3	14.9
Total assets	1,282.9		1,282.9		1,281.9
Intangible intangible assets, net	539.5		539.5		553.1
Mueller Co. [Member]
Segment Reporting Information [Line Items]
Net sales, excluding intercompany	191.3	188.1	356.3	339.2
2013	1.6	1.8	3.2	3.2
Operating income	26.2	23.2	42.1	31.3
Depreciation and amortization	10.1	11.4	21.2	22.6
Restructuring	1.6	0.3	1.7	1.0
2013	6.5	5.5	10.9	8.9
Anvil [Member]
Segment Reporting Information [Line Items]
Net sales, excluding intercompany	96.8	95.0	189.2	189.0
2013	0.1	0.1	0.1	0.1
Operating income	7.5	9.1	14.8	15.0
Depreciation and amortization	3.6	3.5	7.1	7.0
Restructuring	1.1	0.1	1.1	0.1
2013	4.1	3.2	7.2	6.0
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income	(8.4)	(8.0)	(17.6)	(15.1)
Depreciation and amortization	0.1	0.1	0.2	0.2
2013	$ 0.2	$ 0	$ 0.2	$ 0