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
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Compensation and employee benefits	$ 19,580	$ 18,050
Other non-interest expense	$ 2,450	1,550
Previously Reported
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Compensation and employee benefits		16,525
Other non-interest expense		$ 3,075