CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
Conversion of Series B preferred stock to common stock, preferred stock shares converted		318.6225
Conversion of Series B preferred stock to common stock, common stock shares obtained		7,497,000
Repurchase of Series T preferred stock		100,000
Issuance of shares, preferred stock		72,664	318.6225
Issuance of shares of treasury stock for employee stock purchase plan	23,640	3,879
Issuance of shares of treasury stock for restricted stock unit vesting and related tax benefit	6,804
Issuance of shares of common stock as a result of a registered direct offering			12,718,635
Cash dividends, common stock (in dollars per share)	$ 0.24	$ 0.16	$ 0.16
Stock dividends, restricted stock units (in dollars per share)	$ 0.24	$ 0.16	$ 0.08