Components of Net Periodic Benefit Costs Summary of the Impact of Retrospective Application to the Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Compensation and employee benefits	$ 20,343	$ 18,275	$ 39,923	$ 36,325
Other non-interest expense	3,260	1,695	$ 5,710	3,246
Defined contribution plan, employer contribution amount	$ 35,000
Previously Reported
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Compensation and employee benefits		16,750		33,275
Other non-interest expense		$ 3,220		$ 6,296