Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Allowance for doubtful accounts receivables	$ 34,524	$ 23,746
Property, accumulated amortization and depreciation	331,937	317,827
Other intangible assets, accumulated amortization	$ 65,576	$ 63,099
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	129,766,091	129,766,091
Common stock held by subsidiaries, shares	11,293,254	10,747,142
Series A Preferred Stock [Member]
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Series B Preferred Stock [Member]
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0