Business Combinations Acquired Impaired and NonImpaired Loans at Acquisition Date (Details) (Citizens Republic Bancorp, USD $) In Thousands, unless otherwise specified	Apr. 12, 2013
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	$ 4,617,004
Acquired Loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	4,617,004
Acquired Loans | Commercial Real Estate Construction Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	30,534
Acquired Loans | Commercial Real Estate
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	737,635
Acquired Loans | Commercial and Industrial
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	1,753,934
Acquired Loans | Consumer Home Equity Lines Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	364,863
Acquired Loans | Installment
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	1,219,343
Acquired Loans | Residential Mortgages
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	510,695
Acquired performing loans | Commercial Real Estate Construction Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	17,135
Acquired performing loans | Commercial Real Estate Other Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	359,066
Acquired performing loans | Commercial and Industrial
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	1,660,199
Acquired performing loans | Consumer Home Equity Lines Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	317,250
Acquired performing loans | Installment
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	1,165,235
Acquired performing loans | Residential Mortgages
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	278,404
Acquired Impaired Loans | Commercial Real Estate Construction Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	13,399
Acquired Impaired Loans | Commercial Real Estate Other Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	378,569
Acquired Impaired Loans | Commercial and Industrial
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	93,735
Acquired Impaired Loans | Consumer Home Equity Lines Financing Receivable
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	47,613
Acquired Impaired Loans | Installment
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	54,108
Acquired Impaired Loans | Residential Mortgages
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	232,291
non-impaired
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	3,797,289
Impaired loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	819,715
Consumer Loan | Acquired Loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	2,094,901
Consumer Loan | Acquired performing loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	1,760,889
Consumer Loan | Acquired Impaired Loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	334,012
Commercial Loan | Acquired loan type [Domain]
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	2,522,103
Commercial Loan | Acquired performing loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	2,036,400
Commercial Loan | Acquired Impaired Loans
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Fair Value	$ 485,703