Consolidated Statements Of Income (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues [Abstract]
Finance charges	$ 630.4	$ 590.4	$ 538.2
Premiums earned	52.3	51.5	47.1
Other Income	40.8	40.2	23.9
Total revenue	723.5	682.1	609.2
Costs and expenses [Abstract]
Salaries and wages	100.2	87.3	82.2
General and administrative	34.3	34.4	30.5
Sales and marketing	36.8	34.5	31.2
Provision for credit losses	12.8	21.9	24.0
Interest	56.7	65.0	63.4
Provision for claims	40.0	40.8	34.8
Gain (loss) on extinguishment of debt	21.8	0	0
Total costs and expenses	302.6	283.9	266.1
Income before provision for income taxes	420.9	398.2	343.1
Provision for income taxes	154.7	145.1	123.4
Net income	$ 266.2	$ 253.1	$ 219.7
Net income per share [Abstract]
Basic	$ 11.96	$ 10.61	$ 8.65
Diluted	$ 11.92	$ 10.54	$ 8.58
Weighted average Shares Outstanding [Abstract]
Basic	22,257,104	23,850,789	25,409,655
Diluted	22,331,401	24,009,593	25,598,956