Revenues from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 424,927	$ 416,254	$ 1,240,335	$ 1,226,660
United States
Disaggregation of Revenue [Line Items]
Revenues	360,234	351,609	1,050,704	1,030,764
United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	38,164	37,321	109,972	114,972
Canada
Disaggregation of Revenue [Line Items]
Revenues	11,894	12,728	35,050	37,705
Ireland
Disaggregation of Revenue [Line Items]
Revenues	14,505	14,434	44,184	42,521
Other
Disaggregation of Revenue [Line Items]
Revenues	130	162	425	698
Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	114,496	120,310	337,352	351,927
Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	99,034	96,026	288,143	284,955
Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	113,483	102,977	329,675	298,514
Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	47,393	43,462	137,737	130,529
Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	31,046	36,807	94,905	111,433
Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	7,679	4,931	16,209	14,259
Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	11,796	11,741	36,314	35,043
Private Banks
Disaggregation of Revenue [Line Items]
Revenues	114,792	117,250	335,739	351,601
Private Banks | United States
Disaggregation of Revenue [Line Items]
Revenues	74,633	76,864	220,254	229,207
Private Banks | United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	25,234	24,604	71,938	75,649
Private Banks | Canada
Disaggregation of Revenue [Line Items]
Revenues	10,596	10,985	30,723	32,527
Private Banks | Ireland
Disaggregation of Revenue [Line Items]
Revenues	4,329	4,797	12,824	14,218
Private Banks | Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Private Banks | Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	32,256	34,074	95,407	100,498
Private Banks | Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	421	314	1,060	1,299
Private Banks | Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	446	434	1,359	1,172
Private Banks | Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	47,393	43,462	137,737	130,529
Private Banks | Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	27,567	34,018	84,783	103,502
Private Banks | Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	5,663	3,533	11,535	9,896
Private Banks | Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	1,046	1,415	3,858	4,705
Investment Advisors
Disaggregation of Revenue [Line Items]
Revenues	103,189	103,033	299,218	297,916
Investment Advisors | United States
Disaggregation of Revenue [Line Items]
Revenues	103,189	103,033	299,218	297,916
Investment Advisors | United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Canada
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Ireland
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	68,287	72,150	200,718	208,860
Investment Advisors | Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	29,761	26,240	83,726	75,526
Investment Advisors | Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Advisors | Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	5,141	4,643	14,774	13,530
Institutional Investors
Disaggregation of Revenue [Line Items]
Revenues	79,583	80,337	235,309	241,559
Institutional Investors | United States
Disaggregation of Revenue [Line Items]
Revenues	62,699	63,405	185,202	189,383
Institutional Investors | United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	12,930	12,717	38,034	39,323
Institutional Investors | Canada
Disaggregation of Revenue [Line Items]
Revenues	1,298	1,743	4,327	5,178
Institutional Investors | Ireland
Disaggregation of Revenue [Line Items]
Revenues	2,526	2,310	7,321	6,977
Institutional Investors | Other
Disaggregation of Revenue [Line Items]
Revenues	130	162	425	698
Institutional Investors | Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	13,417	13,602	39,628	41,062
Institutional Investors | Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	65,811	66,373	194,445	199,620
Institutional Investors | Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Institutional Investors | Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Institutional Investors | Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Institutional Investors | Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Institutional Investors | Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	355	362	1,236	877
Investment Managers
Disaggregation of Revenue [Line Items]
Revenues	123,846	112,186	359,815	326,037
Investment Managers | United States
Disaggregation of Revenue [Line Items]
Revenues	116,196	104,859	335,776	304,711
Investment Managers | United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Managers | Canada
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Managers | Ireland
Disaggregation of Revenue [Line Items]
Revenues	7,650	7,327	24,039	21,326
Investment Managers | Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Managers | Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	180	161	536	550
Investment Managers | Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Managers | Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	113,037	102,543	328,316	297,342
Investment Managers | Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investment Managers | Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	3,479	2,789	10,122	7,931
Investment Managers | Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	2,016	1,398	4,674	4,363
Investment Managers | Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	5,134	5,295	16,167	15,851
Investments In New Businesses
Disaggregation of Revenue [Line Items]
Revenues	3,517	3,448	10,254	9,547
Investments In New Businesses | United States
Disaggregation of Revenue [Line Items]
Revenues	3,517	3,448	10,254	9,547
Investments In New Businesses | United Kingdom
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Canada
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Ireland
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues	356	323	1,063	957
Investments In New Businesses | Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues	3,041	3,099	8,912	8,510
Investments In New Businesses | Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Professional services fees
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Investments In New Businesses | Account fees and other
Disaggregation of Revenue [Line Items]
Revenues	$ 120	$ 26	$ 279	$ 80