Commitments, Contingencies And Guarantees (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating leases, rent expense	$ 7,700	$ 7,300	$ 7,100
Outstanding purchase commitments expected to fund in the next 12 months	180,500
Notional amount of underlying swaps	3,254,921	1,963,178
Financial Standby Letter of Credit [Member]
Carrying value of the guarantee obligations, liability	2,700
Commitments outstanding	353,905	$ 387,811
State Tax Credits [Member]
Purchases of state tax credits	80,900
Sales of state tax credits	71,600
Risk Participation Agreement [Member]
Carrying value of the guarantee obligations, liability	93
Notional amount of underlying swaps	$ 87,400
Risk Participation Agreement [Member] | Minimum [Member]
Risk Participation Agreements, Term	2 years
Risk Participation Agreement [Member] | Maximum [Member]
Risk Participation Agreements, Term	11 years