Employee Compensation and Benefit Plans - Additional Information (Details) - USD ($)		12 Months Ended
	Jan. 04, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Benefits Disclosure [Line Items]
Maximum percentage of base salary that may be deferred under the DC Plan		50.00%
Maximum percentage of eligible bonus payment that may be deferred under the DC Plan		100.00%
Deferrals under the DC Plan		$ 5,800,000	$ 6,900,000	$ 5,500,000
DC Plan investment gains (losses)		$ 8,500,000	(6,900,000)	1,700,000
Amortization period		30 years
EHOP loan term, option one		5 years
EHOP loan term, option three		10 years
Employee Home Ownership Program, Fixed Rate Loan Term, Option Two		30 years
Maximum loan amount percentage lesser of purchase price or the appraised value		85.00%
Employee Home Ownership Program, Loan Term, Option Two		7 years
Employee Home Ownership Program, Fixed Rate Loan Term, Option One		15 years
SVB Leerink
Employee Benefits Disclosure [Line Items]
Incentive Compensation Plan, Deferred Portion Of Compensation Settled In Restricted Stock Awards		25.00%
Incentive Compensation Plan, Deferred Portion Of Compensation Settled In Cash		75.00%
Incentive Compensation Plan, Deferred Compensation Vesting Period		5 years
Retention pool for acquiree employees	$ 60,000,000
Retention Award, Deferred Portion Of Compensation Settled In Cash		50.00%
Retention Award, Deferred Portion Of Compensation Settled In Restricted Stock Awards		50.00%
Vesting period of retention pool for acquiree employees	5 years
Employee Home Ownership Plan | 12 month LIBOR
Employee Benefits Disclosure [Line Items]
Basis spread on EHOP loans		2.25%
Defined Contribution Plan, The 401(k) Plan
Employee Benefits Disclosure [Line Items]
Maximum percentage of pre-tax income employees are allowed to contribute towards 401(k) plan		75.00%
Maximum annual amount allowable for employee contributions		$ 19,500	$ 19,000	$ 18,500
Maximum percentage of employer matching contributions towards 401(k) plan		5.00%
Employee Stock Ownership Plan (ESOP), Plan
Employee Benefits Disclosure [Line Items]
Maximum percentage of employee's eligible pay earned in the fiscal year contributed by the company in cash or common stock towards ESOP		10.00%
ESOP contributions vesting period		5 years