Commitments and Contingent Liabilities - Additional Information (Detail) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 IBM Mainframe Computer Operations and Support Agreement USD ($)	Dec. 31, 2011 IBM Mainframe Computer Operations and Support Agreement JPY (¥)	Dec. 31, 2011 IBM Distributed Computer Mid Range Server Operations and Support Agreement USD ($)	Dec. 31, 2011 IBM Distributed Computer Mid Range Server Operations and Support Agreement JPY (¥)	Dec. 31, 2011 IBM Application Maintenance and Development Services Agreement USD ($)	Dec. 31, 2011 IBM Application Maintenance and Development Services Agreement JPY (¥)	Dec. 31, 2011 Accenture Application Maintenance and Development Services Agreement USD ($)	Dec. 31, 2011 Accenture Application Maintenance and Development Services Agreement JPY (¥)	Dec. 31, 2011 Nippon Telegraph and Telephone Data Corporation Application Maintenance and Development Services USD ($)	Dec. 31, 2011 Nippon Telegraph and Telephone Data Corporation Application Maintenance and Development Services JPY (¥)
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		4 years	4 years	4 years	4 years	6 years	6 years	6 years	6 years	2 years	2 years
Outsourcing agreements, aggregate remaining cost		$ 209.0	¥ 16,200.0	$ 185.0	¥ 14,400.0	$ 134.0	¥ 10,400.0	$ 96.0	¥ 7,500.0	$ 8.0	¥ 600.0
Operating Leases, lease terms	Expire in various years through 2020