Discontinued Operations - Additional information (Detail) (USD $)	3 Months Ended				3 Months Ended			9 Months Ended				9 Months Ended			3 Months Ended				9 Months Ended
	Jun. 30, 2014	Sep. 30, 2014		Dec. 31, 2013	Sep. 30, 2014 Restructuring Charges Member	Sep. 30, 2014 Segment, Discontinued Operations [Member]	Sep. 30, 2013 Segment, Discontinued Operations [Member]	Sep. 30, 2014 Segment, Discontinued Operations [Member]	Sep. 30, 2013 Segment, Discontinued Operations [Member]	Sep. 30, 2014 Segment, Discontinued Operations [Member] Illinois region sale of August 8, 2014 [Member]	Jul. 31, 2014 Segment, Discontinued Operations [Member] Illinois region sale of August 8, 2014 [Member]	Sep. 30, 2014 Segment, Discontinued Operations [Member] Central Florida region sale of September 15, 2014 [Member]	Aug. 31, 2014 Segment, Discontinued Operations [Member] Central Florida region sale of September 15, 2014 [Member]	Sep. 30, 2014 Segment, Discontinued Operations [Member] California region sale of November 8, 2014 [Member] Subsequent Event Member	Sep. 30, 2014 Segment, Discontinued Operations [Member] California region sale of November 8, 2014 [Member] Subsequent Event Member Indemnification Guarantee Member	Sep. 30, 2014 Segment, Continuing Operations [Member] Restructuring Charges Member	Jun. 30, 2014 Segment, Continuing Operations [Member] Restructuring Charges Member	Sep. 30, 2013 Segment, Continuing Operations [Member] Restructuring Charges Member	Sep. 30, 2014 Segment, Continuing Operations [Member] Restructuring Charges Member	Sep. 30, 2013 Segment, Continuing Operations [Member] Restructuring Charges Member
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Restructuring Charges																$ 8,290,000		$ 0	$ 12,864,000	$ 0
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax						25,775,000	0	25,775,000	0	24,600,000		1,200,000
Goodwill Written Off Related To Business Unit To Be Disposed	186,500,000					0	0	186,511,000	0
Estimate Of Restructuring Charges To Be Incurred					41,000,000												54,000,000
Estimate Of Severance Retention And Other Payments To Be Incurred					22,000,000												32,000,000
Estimate Of Operational Set Up Cost And Lease Cancellations To Be Incurred					19,000,000												22,000,000
Branches Sold											12		9	20
Loans held-for-sale		178,008,000	[1]	110,426,000		1,099,673,000		1,099,673,000			562,000,000		104,000,000	1,100,000,000
Deposits		24,466,105,000		26,711,145,000		1,089,046,000		1,089,046,000			726,000,000		217,000,000	1,100,000,000
Maximum Amount Of Future Payments Under Guarantee Percentage															1.5
Guarantee Obligations Term															two years
GuaranteeObligationsOriginAndPurpose															The Corporation also agreed to indemnify the purchaser for up to 1.5% of credit losses on transferred loans for a period of two years after the closing. Pursuant to this indemnification provision, the Corporation’s maximum exposure is approximately $16 million.
Maximum Amount Of Future Payments Under Gurantee															16,000,000
Net Premium On Sale Of California Operations														$ 4,000,000

[1] Loans held-for-sale from discontinued operations are presented as part of "Assets from Discontinued Operations" in the Consolidated Statement of Condition. Refer to Note 3 to the consolidated financial statements for further information on the discontinued operations.