Condensed Consolidated Statements of Financial Conditions $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Current assets:
Cash and cash equivalents	$ 77.1	$ 75.1
Financial investments:
Trading investments, at fair value	0.5	0.5
Available-for-sale investments, at fair value	39.7	47.2
Accounts receivable, net, including $41.3 and $40.3 from related parties at March 31, 2016 and December 31, 2015, respectively	149.6	131.0
Income taxes receivable		16.0
Other receivables	4.6	5.4
Prepaid expenses	5.9	5.1
Total current assets	277.4	280.3
Property and equipment, net	26.6	29.6
Goodwill	735.7	741.3
Intangible assets, net	231.1	239.0
Deferred income taxes, net		0.6
Investment in EuroCCP	11.7	11.4
Other assets	4.5	4.8
Total assets	1,287.0	1,307.0
Current liabilities:
Accounts payable and accrued liabilities, including $15.2 to related parties at both March 31, 2016 and December 31, 2015	91.8	72.9
Section 31 fees payable	78.4	93.0
Current portion of long-term debt	84.2	83.9
Current portion of contingent consideration liability to related party	6.6	6.6
Total current liabilities	261.0	256.4
Long-term debt, less current portion	552.6	593.7
Contingent consideration liability to related party, less current portion	53.1	58.8
Unrecognized tax benefits	7.7	8.0
Deferred income taxes	1.1	7.4
Other liabilities	$ 2.9	$ 2.8
Commitments and contingencies
Stockholders' equity:
Common stock, $0.01 par value. 362,500,000 voting and 29,000,000 non-voting shares authorized at March 31, 2016 and December 31, 2015; 75,679,753 voting and 21,146,136 non-voting shares issued at March 31, 2016; 74,991,528 voting and 21,146,136 non-voting shares issued at December 31, 2015	$ 1.0	$ 1.0
Common stock in treasury, at cost, 462,879 and 458,237 voting shares at March 31, 2016 and December 31, 2015, respectively	(6.6)	(6.5)
Additional paid-in capital	272.4	270.6
Retained earnings	155.1	125.0
Accumulated other comprehensive loss, net	(13.3)	(10.2)
Total stockholders' equity	408.6	379.9
Total liabilities and stockholders' equity	$ 1,287.0	$ 1,307.0
Stockholders' Equity Note, Stock Split, Conversion Ratio	0.3436	0.3436