XML 71 R54.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Commitments, Contingencies and Other Matters - Additional Information (Detail) (USD $)
In Millions
Jun. 30, 2011
Commitments and Contingencies Disclosure [Line Items]  
Letters of credit, collateral for retrospective premiums and retained losses $ 40.6
Commitments to purchase major equipment $ 366