Allowance for Non-Covered Loan Loss and Credit Quality (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Unallocated allowance, maximum percentage	5.00%
Secured loan portfolio, percentage	79.00%	79.00%
Deferred loan fees	$ 11,636,000	$ 12,523,000	$ 11,400,000
External appraisal considered stale requiring a new appraisal, years	1 year
Loans past due as to maturity, days	90 days
Financing Receivable Modifications Recorded Investments	99,710,000	101,778,000
Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
External appraisal, months	6 months
Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
External appraisal, months	9 months
Restructured Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable Modifications Recorded Investments	74,100,000	70,600,000
Percentage of loan collateral balance	100.00%
Available commitments for troubled debt restructurings outstanding	$ 0	$ 0
Non-Homogeneous [Member] | Minimal Risk [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	1
Non-Homogeneous [Member] | Low Risk [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	2
Non-Homogeneous [Member] | Modest Risk [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	3
Non-Homogeneous [Member] | Average Risk [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	4
Non-Homogeneous [Member] | Acceptable Risk [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	5
Non-Homogeneous [Member] | Pass/Watch [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	6
Non-Homogeneous [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	7
Non-Homogeneous [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8
Non-Homogeneous [Member] | Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	9
Non-Homogeneous [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10
Homogeneous [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Duration of time account is past due before risk rating is applied	30 days
Homogeneous [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	7
Homogeneous [Member] | Special Mention [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	30 days
Homogeneous [Member] | Special Mention [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	59 days
Homogeneous [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8
Homogeneous [Member] | Substandard [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	60 days
Homogeneous [Member] | Substandard [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	119 days
Homogeneous [Member] | Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	9
Homogeneous [Member] | Doubtful [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	120 days
Homogeneous [Member] | Doubtful [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	149 days
Homogeneous [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10
Homogeneous [Member] | Loss [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	150 days
Homogeneous Retail [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	7
Homogeneous Retail [Member] | Special Mention [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	30 days
Homogeneous Retail [Member] | Special Mention [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	89 days
Homogeneous Retail [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8
Homogeneous Retail [Member] | Substandard [Member] | Open-End Loan [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	90 days
Homogeneous Retail [Member] | Substandard [Member] | Open-End Loan [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	180 days
Homogeneous Retail [Member] | Substandard [Member] | Closed-End Loan [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	90 days
Homogeneous Retail [Member] | Substandard [Member] | Closed-End Loan [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	120 days
Homogeneous Retail [Member] | Loss [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10
Homogeneous Retail [Member] | Loss [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	120 days
Homogeneous Retail [Member] | Loss [Member] | Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	180 days
Homogeneous Retail [Member] | Loss [Member] | Open-End Loan [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	180 days
Homogeneous Retail [Member] | Loss [Member] | Closed-End Loan [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator	120 days