Income Taxes (Components Of United's Deferred Tax Assets And Liabilities) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Allowance for credit losses	$ 41,853	$ 41,979
Other accrued liabilities	29	30
Unrecognized components of net periodic pension costs	21,696	19,480
Unrealized loss on securities available for sale	16,703	19,492
Net operating loss	846	3,113
Total deferred tax assets	81,127	84,094
Deferred tax liabilities:
Purchase accounting intangibles	6,436	7,230
Deferred mortgage points	377	1,039
Accrued benefits payable	10,961	12,587
Premises and equipment	857	1,351
Other	2,764	1,723
Total deferred tax liabilities	21,395	23,930
Net deferred tax assets	$ 59,732	$ 60,164