Stock and Other Incentive Plans (Details Textual) (USD $)	12 Months Ended																		3 Months Ended					12 Months Ended			3 Months Ended	0 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Restricted Stock and Performance Based Awards [Member]	Dec. 31, 2011 Restricted Stock and Performance Based Awards [Member]	Dec. 31, 2010 Restricted Stock and Performance Based Awards [Member]	Dec. 31, 2012 Stock Incentive Plan [Member]	Dec. 31, 2011 Stock Incentive Plan [Member]	Dec. 31, 2010 Stock Incentive Plan [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Director [Member]	Dec. 31, 2011 Stock Incentive Plan [Member] Director [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Director [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock [Member]	Dec. 31, 2011 Stock Incentive Plan [Member] Restricted Stock [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Restricted Stock [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Restricted Stock [Member] Director [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock [Member] Minimum [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock [Member] Maximum [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Performance Shares [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Performance Shares [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Performance Shares [Member] Minimum [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Performance Shares [Member] Maximum [Member]	Dec. 31, 2010 Stock Incentive Plan [Member] Performance Shares [Member] Weighted Average [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock and Performance Based Awards [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock and Performance Based Awards [Member] Minimum [Member]	Dec. 31, 2012 Stock Incentive Plan [Member] Restricted Stock and Performance Based Awards [Member] Maximum [Member]	Dec. 31, 2012 Executive Incentive Program [Member] Performance Shares [Member] executive_officer	Jul. 31, 2012 Executive Incentive Program [Member] Performance Shares [Member] Minimum [Member]	Jul. 31, 2012 Executive Incentive Program [Member] Performance Shares [Member] Maximum [Member]	Dec. 31, 2012 Dividend Reinvestment Plan [Member]	Dec. 31, 2011 Dividend Reinvestment Plan [Member]	Dec. 31, 2010 Dividend Reinvestment Plan [Member]	Dec. 31, 2012 Employee Stock Purchase Plan [Member]	Dec. 31, 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2010 Employee Stock Purchase Plan [Member]	Jan. 02, 2013 Subsequent Event [Member] Executive Incentive Program [Member] Performance Shares [Member] executive_officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorization of common shares to issue							2,390,272																							1,000,000
Common shares issued, net of forfeitures							1,576,632	1,182,074	1,091,007
Number of shares authorized							813,640	1,208,198	1,299,265																								169,099	232,218	278,798
Award vesting period										3 years							3 years	8 years			3 years	8 years	6 years		3 years	8 years	3 years						27 months
Share-based compensation expense										$ 600,000	$ 500,000	$ 600,000	$ 2,500,000	$ 2,200,000	$ 1,600,000
Shareholder return performance period used to measure award																												1 year	3 years
Number of executive officers granted awards																											5
Number of executive officers eligible for awards																																				6
Granted in period																											2,700,000
Granted in period (in shares)				397,917	106,569	175,412																					112,000
Value of performance based awards released																			3,600,000	1,400,000
401(k) Plan [Abstract]
Percentage of matching contribution	3.00%
Value of matching contribution	400,000	0	300,000
Weighted average amortization period remaining																								4 years 9 months 18 days
Shares issued under the plan										27,900	27,400	25,400							154,700	67,800
Withheld of common stock													3,359	4,576	520
Number of restricted shares vested upon the retirement of a member of the board of directors				58,531	44,211	20,948										6,586
Total DRIP shares issued under the Plan																														503,043
Total shares issued under the Dividend Reinvestment Plan																														16,732	18,791	19,267
Value of shares available for grant each year																																	25,000
Discount on market price on the date of grant	85.00%																																85.00%
Discount on market price on the date of exercise	85.00%																																85.00%
Cash received from employees upon exercising options																																	$ 1,000,000	$ 200,000	$ 200,000