Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012 Y
Commitments And Contingencies [Line Items]
Additional successive terms extendable at the option			4
Period of extendable lease term, in years			5 years
Sale leaseback transaction, gain recognized over lease term	$ 79.9	$ 87.4
Loan commitments	1,237		1,253
Fixed rate loan commitment	1,190
Floating rate loan commitment	47
Standby letters of credit	71.5		63.4
Loan commitments fixed interest rate, minimum	0.00%
Loan commitments fixed interest rate, maximum	26.25%
Allowance for unfunded loan commitments	2.4		4.0
Extended credit	13.7		13.3
Credit extensions with collateral	$ 10.4		$ 11.2
Minimum [Member]
Commitments And Contingencies [Line Items]
Lease Term	1 year
Minimum [Member] | Indiana Community Bancorp [Member]
Commitments And Contingencies [Line Items]
Lease Term	5 years
Maximum [Member]
Commitments And Contingencies [Line Items]
Lease Term	24 years
Maximum [Member] | Indiana Community Bancorp [Member]
Commitments And Contingencies [Line Items]
Lease Term	24 years