Preparation of Interim Financial Statements (Details) $ in Thousands		6 Months Ended	12 Months Ended
	Jan. 01, 2020 USD ($)	Jun. 30, 2020 USD ($) financial_center	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number of financial centers | financial_center		226
Allowance for credit loss		$ 231,643	$ 68,244
Unfunded commitments, allowance for credit loss		24,400	8,400
Cumulative effect on retained earnings		$ 819,153	$ 848,848
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Impact of ASU 2016-13 adoption
Lessee, Lease, Description [Line Items]
Allowance for credit loss	$ 151,400
Unfunded commitments, allowance for credit loss	24,000
Debt securities, allowance for credit loss	742
Cumulative effect on retained earnings	128,100
Purchased with credit deterioration, allowance for credit loss	$ 5,400