Recent Accounting Developments (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201708Member
Allowance for credit losses	$ 373,174	$ 161,901			$ 158,461
Allowance for loan losses	373,109	161,901	$ 253,412		158,461	$ 159,622	$ 154,164
Allowance for held-to-maturity securities losses	65	0			0
Financial assets held at amortized cost, accrued interest	109,100
Cumulative effect adjustment from the adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses				$ 47,400
Allowance for loan losses					47,344
Allowance for held-to-maturity securities losses				74
Loans acquired with deteriorated credit quality
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses		531
Loans acquired with deteriorated credit quality | Cumulative effect adjustment from the adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses				11,000
Loans acquired without deteriorated credit quality | Cumulative effect adjustment from the adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses				3,200
Unfunded lending-related commitments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses	59,599	1,480			1,633
Unfunded lending-related commitments | Cumulative effect adjustment from the adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses				33,200
Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses	$ 313,510	$ 160,421			$ 156,828
Loans | Cumulative effect adjustment from the adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses				$ 14,200