Condensed Consolidated Statement of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues:
Transaction fees	$ 111,926	$ 144,823	$ 347,863	$ 345,162
Access fees	13,019	13,062	39,447	40,119
Exchange services and other fees	11,513	10,978	34,263	30,443
Market data fees	8,222	7,133	24,363	22,702
Regulatory fees	9,116	8,204	27,436	25,332
Other revenue	2,411	2,835	8,494	14,841
Total Operating Revenues	156,207	187,035	481,866	478,599
Operating Expenses:
Compensation and benefits	28,344	29,583	83,980	79,158
Depreciation and amortization	10,200	12,394	34,311	34,071
Technology support services	5,608	5,342	16,944	15,480
Professional fees and outside services	21,381	12,619	49,758	37,163
Royalty fees	19,399	21,840	57,849	52,744
Order routing	536	581	557	1,994
Travel and promotional expenses	2,610	1,407	7,616	6,434
Facilities costs	1,322	874	4,268	3,552
Other expenses	1,157	1,285	3,485	3,969
Total Operating Expenses	90,557	85,925	258,768	234,565
Operating Income	65,650	101,110	223,098	244,034
Other Income/(Expense):
Investment and other income	1,557	68	7,921	177
Net income from investments	306	289	830	165
Interest and other borrowing costs	(177)	(16)	(232)	(16)
Total Other Income	1,686	341	8,519	326
Income Before Income Taxes	67,336	101,451	231,617	244,360
Income tax provision	26,885	33,935	91,059	89,739
Net Income	40,451	67,516	140,558	154,621
Net loss attributable to noncontrolling interests	270	0	792	0
Net Income Excluding Noncontrolling Interests	40,721	67,516	141,350	154,621
Change in redemption value of noncontrolling interest	(270)	0	(792)	0
Net income allocated to participating securities	171	297	584	676
Net Income allocated to common stockholders	$ 40,280	$ 67,219	$ 139,974	$ 153,945
Net Income Per Share Allocated to Common Stockholders:
Basic	$ 0.50	$ 0.81	$ 1.72	$ 1.85
Diluted	$ 0.50	$ 0.81	$ 1.72	$ 1.85
Diluted EPS Denominator:
Basic	81,285	82,755	81,481	83,329
Diluted	81,285	82,755	81,481	83,329