Consolidated Statements Of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues [Abstract]
Finance charges	$ 730.5	$ 630.4	$ 590.4
Premiums earned	48.2	52.3	51.5
Other Income	46.6	40.8	40.2
Total revenue	825.3	723.5	682.1
Costs and expenses [Abstract]
Salaries and wages	116.4	100.2	87.3
General and administrative	37.8	34.3	34.4
Sales and marketing	45.9	36.8	34.5
Provision for credit losses	41.5	12.8	21.9
Interest	76.0	56.7	65.0
Provision for claims	33.2	40.0	40.8
Loss on extinguishment of debt	0.0	21.8	0.0
Total costs and expenses	350.8	302.6	283.9
Income before provision for income taxes	474.5	420.9	398.2
Provision for income taxes	174.8	154.7	145.1
Net income	$ 299.7	$ 266.2	$ 253.1
Net income per share [Abstract]
Basic	$ 14.35	$ 11.96	$ 10.61
Diluted	$ 14.28	$ 11.92	$ 10.54
Weighted average Shares Outstanding [Abstract]
Basic	20,891,695	22,257,104	23,850,789
Diluted	20,980,753	22,331,401	24,009,593