Common Stock (Outstanding Performance Share Awards) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years		Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance shares lapsed, Number Outstanding	0
Performance shares lapsed, Weighted Average Grant Date Fair Value	$ 0.00
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Shares Payout Level	100.00%
Share based compensation, outstanding at beginning of period (in shares)	219,800
Performance shares awards, Number Outstanding	112,164
Performance shares vested, Number Outstanding	(36,350)
Performance shares forfeited, Number Outstanding	0
Share based compensation, outstanding at end of period (in shares)	295,614		219,800
Performance shares outstanding, Weighted Average Grant Date Fair Value, Beginning of Period	$ 15.86
Performance shares awards, Weighted Average Grant Date Fair Value	$ 23.45		$ 19.82	$ 12.00
Performance shares vested, Weighted Average Grant Date Fair Value	$ 17.27
Performance shares forfeited, Weighted Average Grant Date Fair Value	$ 0.00
Performance shares outstanding, Weighted Average Grant Date Fair Value, End of Period	$ 18.57		$ 15.86
Performance shares outstanding, Unrecognized Compensation Expense	$ 1,825	[1]
Performance shares outstanding, Aggregate Intrinsic Value	$ 10,240
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1

[1] The unrecognized compensation expense is expected to be recognized over the weighted average remaining contractual term of the awards of approximately one year.