CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Professional service revenues	$ 129	$ 120
Insurance service revenues	732	688
Total revenues	861	808
Costs and operating expenses:
Insurance costs	641	609
Cost of providing services (exclusive of depreciation and amortization of intangible assets)	57	57
Sales and marketing	39	49
General and administrative	31	25
Systems development and programming costs	13	11
Depreciation	8	6
Amortization of intangible assets	1	1
Total costs and operating expenses	790	758
Operating income	71	50
Other income (expense):
Interest expense, bank fees and other, net	(4)	(5)
Income before provision for income taxes	67	45
Income tax expense	13	16
Net income	54	29
Comprehensive income	$ 54	$ 29
Net income per share:
Basic (in dollars per share)	$ 0.77	$ 0.42
Diluted (in dollars per share)	$ 0.75	$ 0.41
Weighted average shares:
Basic (in shares)	70,047,752	68,509,328
Diluted (in shares)	72,274,821	70,913,970