Stock Based Compensation (Details Textuals) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for vesting of stock options			$ 5.6
Restricted stock vest period after CPP fully paid, Minimum	9 months
Restricted stock vest period after CPP fully paid, Maximum	28 months
Stock Based Compensation (Textuals) [Abstract]
Total fair value of vested stock options	3.3		3.6
Percent In Restricted Shares Vested In Increments As Funds Are Paid	25.00%
Pattern in which restricted shares vests, when CPP paid	0% vest when less than 25% is repaid, 25%vest when 25-49% is repaid, 50% vest when 50-74% is repaid, 75% vest when 75-99% is repaid, and 100% repaidvest when the full amount is repaid
Average cost per share, salary share	$ 14.25	$ 13.55	$ 13.43
Number of highly compensated employees to be vested in future	20
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for vesting of stock options	2.6	1.7	3.4
Unvested share-based payment awards	10.6
Total compensation cost not yet recognized, period for recognition	Fourth quarter 2013
Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for vesting of stock options	3.1	2.8
Unvested share-based payment awards	9.6
Total compensation cost not yet recognized, period for recognition	Fourth quarter 2013
Restricted stock vest in years after CPP fully paid.	3 years
Minimum period required to perform substantial services for getting award	2 years
Salary Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for vesting of stock options	$ 2.0	$ 1.4	$ 3.3

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