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

Operating Segment Information and Concentrations of Risk (Details)

v2.4.0.6
Operating Segment Information and Concentrations of Risk (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Mar. 31, 2010
Segment Reporting Information [Line Items]      
Net sales $ 1,237.5 $ 1,167.0 $ 1,124.6
Total operating income (loss) 155.5 104.7 (21.0)
Net interest expense (7.4) (4.4) (4.0)
Other income (expense) 3.0 (3.7) 6.3
Total identifiable assets 2,310.0 1,960.6  
USA & Europe Fibre Cement [Member]
      
Segment Reporting Information [Line Items]      
Net sales 862.0 814.0 828.1
Total operating income (loss) 148.4 160.3 208.5
Total identifiable assets 749.1 752.0  
Asia Pacific Fibre Cement [Member]
      
Segment Reporting Information [Line Items]      
Net sales 375.5 353.0 296.5
Total operating income (loss) 80.3 79.4 58.7
Total identifiable assets 238.4 235.0  
Research and Development [Member]
      
Segment Reporting Information [Line Items]      
Total operating income (loss) (20.7) (20.1) (19.0)
Total identifiable assets 15.6 14.4  
General Corporate [Member]
      
Segment Reporting Information [Line Items]      
Total operating income (loss) (52.5) (114.9) (269.2)
Total identifiable assets 1,306.9 959.2  
Segments Total [Member]
      
Segment Reporting Information [Line Items]      
Total operating income (loss) 208.0 219.6 248.2
Total identifiable assets 1,003.1 1,001.4  
Worldwide Total [Member]
      
Segment Reporting Information [Line Items]      
Net sales 1,237.5 1,167.0 1,124.6
Total operating income (loss) 151.1 96.6 (18.7)
Total identifiable assets 2,310.0 1,960.6  
USA [Member]
      
Segment Reporting Information [Line Items]      
Net sales 833.9 789.2 808.9
Total identifiable assets 748.5 752.1  
Australia [Member]
      
Segment Reporting Information [Line Items]      
Net sales 282.4 266.4 214.3
Total identifiable assets 160.5 155.5  
New Zealand [Member]
      
Segment Reporting Information [Line Items]      
Net sales 54.4 52.9 50.6
Total identifiable assets 43.7 45.8  
Other Countries [Member]
      
Segment Reporting Information [Line Items]      
Net sales 66.8 58.5 50.8
Total identifiable assets $ 50.4 $ 48.0