Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Operating Segment Information and Concentrations of Risk (Details Textual)

v2.4.0.6
Operating Segment Information and Concentrations of Risk (Details Textual)
In Millions, unless otherwise specified
12 Months Ended
Mar. 31, 2012
USD ($)
Mar. 31, 2012
AUD
Mar. 31, 2011
USD ($)
Mar. 31, 2010
USD ($)
Mar. 31, 2012
USA & Europe Fibre Cement [Member]
USD ($)
Mar. 31, 2011
USA & Europe Fibre Cement [Member]
USD ($)
Mar. 31, 2010
USA & Europe Fibre Cement [Member]
USD ($)
Mar. 31, 2012
Asia Pacific Fibre Cement [Member]
USD ($)
Mar. 31, 2011
Asia Pacific Fibre Cement [Member]
USD ($)
Mar. 31, 2010
Asia Pacific Fibre Cement [Member]
USD ($)
Mar. 31, 2012
Research and Development [Member]
USD ($)
Mar. 31, 2011
Research and Development [Member]
USD ($)
Mar. 31, 2010
Research and Development [Member]
USD ($)
Mar. 31, 2012
AICF [Member]
USD ($)
Mar. 31, 2011
AICF [Member]
USD ($)
Mar. 31, 2010
AICF [Member]
USD ($)
Mar. 31, 2012
General Corporate [Member]
USD ($)
Mar. 31, 2011
General Corporate [Member]
USD ($)
Mar. 31, 2010
General Corporate [Member]
USD ($)
Segment Reporting Information [Line Items]                                      
Research and development expenses $ 30.4   $ 28.0 $ 27.1 $ 10.1 $ 9.7 $ 10.4 $ 1.6 $ 1.4 $ 1.0 $ 18.7 $ 16.9 $ 15.7            
Unfavorable asbestos adjustment 15.8   85.8 224.2                         15.8 85.8 224.2
Net interest (expense) income (7.4)   (4.4) (4.0)                   3.3 4.3 3.3      
Selling, general and administrative expenses 191.0   173.4 185.8             2.0 3.2 3.3            
Impairment charges 14.3       14.3                            
Value of Asbestos related assets                                 825.2 819.7  
Operating Segment Information and Concentrations of Risk (Textual) [Abstract]                                      
Accounts receivable major customer percentage 21.00% 21.00% 20.00%                                
AICF SG&A expenses 2.8 2.7 2.2 2.1                              
ASIC expense (recoveries), net $ 1.1   $ (8.7) $ 3.4                              
Percentage of net sales 33.00% 33.00%