Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Allowance for doubtful accounts receivables	$ 36,649	[1]	$ 27,130	[1]	$ 40,164	[1]	$ 23,746
Property, accumulated amortization and depreciation	402,471		367,545
Other intangible assets, accumulated amortization	$ 70,155		$ 68,305
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	112,766,091		112,766,091
Common stock held by subsidiaries, shares	7,728,387		8,513,493
Series A Preferred Stock [Member]
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0		0
Series B Preferred Stock [Member]
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0		0

[1] The allowance for doubtful accounts balances are substantially all related to M&A and Restructuring fee receivables that include recoverable expense receivables.