CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
REVENUES
Commissions and fees	$ 2,009,857	$ 1,857,270	$ 1,762,787
Investment income	2,746	1,626	1,456
Other income, net	1,643	22,451	2,386
Total revenues	2,014,246	1,881,347	1,766,629
EXPENSES
Employee compensation and benefits	1,068,914	994,652	925,217
Non-cash stock-based compensation	33,519	30,631	16,052
Other operating expenses	332,118	283,470	262,872
(Gain)/loss on disposal	(2,175)	(2,157)	(1,291)
Amortization	86,544	85,446	86,663
Depreciation	22,834	22,698	21,003
Interest	40,580	38,316	39,481
Change in estimated acquisition earn-out payables	2,969	9,200	9,185
Total expenses	1,551,784	1,431,625	1,343,130
Income before income taxes	462,462	449,722	423,499
Income taxes	118,207	50,092	166,008
Net income	$ 344,255	$ 399,630	$ 257,491
Net income per share:
Basic (in dollars per share)	$ 1.24	$ 1.43	$ 0.92
Diluted (in dollars per share)	1.22	1.40	0.91
Dividends declared per share (in dollars per share)	$ 0.31	$ 0.28	$ 0.25