Shareholders' Equity (Market prices per share on a national securities exchange as vesting condition) (Details) (USD $)	6 Months Ended
	Mar. 31, 2013
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	533,919
Fifth Anniversary | Ten Dollar Per Share Market Price
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	149,676
Weighted average fair value per share restricted stock	10
Fourth Anniversary | Ten Dollar Per Share Market Price
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	191,573
Weighted average fair value per share restricted stock	10
Fourth Anniversary | Seventeen Dollars And Fifty Cents Per Share Market Price
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	136,000
Weighted average fair value per share restricted stock	17.50
Fourth Anniversary | Twenty Dollar Per Share Market Price
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	8,500
Weighted average fair value per share restricted stock	20
Fourth Anniversary | Twenty Two Dollars And Fifty Cents Per Share Market Price
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	19,000
Weighted average fair value per share restricted stock	22.50
No Vesting | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units subject to vesting conditions	29,170