Business Combinations Business Combinations (Acquired Impaired and Non-Impaired Loans at Acquisition Date) (Details) (Citizens Republic Bancorp, USD $) In Thousands, unless otherwise specified	12 Months Ended																						0 Months Ended							12 Months Ended
	Dec. 31, 2013	Apr. 12, 2013	Apr. 12, 2013 Acquired Impaired Loans	Apr. 12, 2013 Acquired Impaired Loans Commercial and Industrial Financing Receivable	Apr. 12, 2013 Acquired Impaired Loans Commercial Real Estate Other Receivable	Apr. 12, 2013 Acquired Impaired Loans Commercial Real Estate Construction Financing Receivable	Apr. 12, 2013 Acquired Impaired Loans Residential Mortgage	Apr. 12, 2013 Acquired Impaired Loans Consumer Installment Financing Receivable	Apr. 12, 2013 Acquired Impaired Loans Consumer Home Equity Lines Financing Receivable	Apr. 12, 2013 Acquired performing loans Commercial and Industrial Financing Receivable	Apr. 12, 2013 Acquired performing loans Commercial Real Estate Other Receivable	Apr. 12, 2013 Acquired performing loans Commercial Real Estate Construction Financing Receivable	Apr. 12, 2013 Acquired performing loans Residential Mortgage	Apr. 12, 2013 Acquired performing loans Consumer Installment Financing Receivable	Apr. 12, 2013 Acquired performing loans Consumer Home Equity Lines Financing Receivable	Apr. 12, 2013 Acquired Loans	Apr. 12, 2013 Acquired Loans Commercial and Industrial Financing Receivable	Apr. 12, 2013 Acquired Loans Commercial Real Estate Other Receivable	Apr. 12, 2013 Acquired Loans Commercial Real Estate Construction Financing Receivable	Apr. 12, 2013 Acquired Loans Residential Mortgage	Apr. 12, 2013 Acquired Loans Consumer Installment Financing Receivable	Apr. 12, 2013 Acquired Loans Consumer Home Equity Lines Financing Receivable	Apr. 12, 2013 non-impaired [Member]	Apr. 12, 2013 Commercial Loan Acquired Impaired Loans	Apr. 12, 2013 Commercial Loan Acquired performing loans	Apr. 12, 2013 Commercial Loan Acquired Loans	Apr. 12, 2013 Consumer Loan Acquired Impaired Loans	Apr. 12, 2013 Consumer Loan Acquired performing loans	Apr. 12, 2013 Consumer Loan Acquired Loans	Dec. 31, 2013 Loans and Finance Receivables [Member]
Acquired Impaired and Non-Impaired Loans at Acquisition Date [Line Items]
Business Combination, Acquired Receivables, Gross Contractual Amount																							$ 4,017,304
Goodwill, Purchase Accounting Adjustments	5,400																						220,015							(7,300)
Business Combination, Acquired Receivables, Fair Value		$ 4,617,004	$ 819,715	$ 93,735	$ 378,569	$ 13,399	$ 232,291	$ 54,108	$ 47,613	$ 1,660,199	$ 359,066	$ 17,135	$ 278,404	$ 1,165,235	$ 317,250	$ 4,617,004	$ 1,753,934	$ 737,635	$ 30,534	$ 510,695	$ 1,219,343	$ 364,863	$ 3,797,289	$ 485,703	$ 2,036,400	$ 2,522,103	$ 334,012	$ 1,760,889	$ 2,094,901