Shareholders' Equity (Narrative) (Details) (USD $)	0 Months Ended			3 Months Ended			6 Months Ended		12 Months Ended
	Apr. 21, 2010	Mar. 31, 2010	Feb. 03, 2010	Jun. 30, 2011	Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Apr. 20, 2010
Common stock raised through a public offer			$ 303,600,000						$ 89,786,000
Common stock shares raised through a public offer			8,625,000
Common stock, shares pursuant to the underwriters' over-allotment option			1,125,000
Underwriter's over-allotment option price per share			$ 11.00
Common stock, depository shares			18,975,000
Common stock, depository shares pursuant to underwriters over-allotment option			2,475,000
Common stock, depository share price per share			$ 11.00
Depository shares, fractional interests			0.01
Proceeds from issuance of common and preferred stock, net			288,100,000
Redeemed fixed rate cumulative perpetual preferred stock						214,200,000			214,181,000
Repurchase of warrants issued to U.S. Treasury		4,500,000							4,500,000
Common stock, shares authorized	200,000,000			200,000,000			200,000,000		200,000,000	100,000,000
Conversion of preferred stock to common stock, shares	100
Compensation cost relates to stock options, restricted stock and restricted stock units				868,000	799,000		1,987,000	1,425,000
Total income tax benefit recognized related to stock-based compensation				347,000	320,000		795,000	570,000
Restricted stock share based compensation arrangement by share based payment award award vesting period							5
Total intrinsic value of options exercised				32,000	93,000		147,000	382,000
Cash received from exercise of stock options				97,000	153,000		309,000	917,000
Total fair value of restricted stock units vested and released				0	0
Restricted stock units at fair value							677,000	213,000
Total unrecognized compensation cost related to nonvested stock options				3,200,000			3,200,000
Income tax benefits received				58,000	54,000		633,000	380,000
Tax deficiency from stock options exercised							251,000	205,000
Nonvested Stock [Member]
Expected recognized over a weighted-average period, years							2.9
Preferred Stock [Member]
Common stock, depository shares outstanding			18,975,000
Restricted Stock [Member]
Total fair value of restricted stock units vested and released				114,000	51,000		765,000	538,000
Total unrecognized compensation cost related to nonvested stock options				4,600,000			4,600,000
Expected recognized over a weighted-average period, years							3.0
Nonvested Restricted Stock Units (RSUs) [Member]
Total unrecognized compensation cost related to nonvested stock options				$ 1,000,000			$ 1,000,000
Expected recognized over a weighted-average period, years							1.6