Retirement Benefits (Narrative) (Detail) (Retirement Savings Plan [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012
Retirement Savings Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum employee contribution rate, pretax			50.00%
Safe harbor non-elective contribution rate			3.00%
Matching contribution rate			6.00%
Matching and profit contribution vesting rate			25.00%
Contributions to defined benefit pension plans	$ 1.8	$ 2.2	$ 4.2	$ 4.3
Estimated expense relating to retirement savings plan for the year 2013					$ 5.0