Commitments, Contingencies, and Guarantees (Credit commitments) (Details 1) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Credit Commitments [Line Items]
Credit Commitments	$ 2,859,279
Unfunded Commitments to Extend Credit
Credit Commitments [Line Items]
Credit Commitments	2,780,724
Standby Letters of Credit
Credit Commitments [Line Items]
Credit Commitments	60,519
Assets secured for standby letters of credit	39,800
Commercial Letters of Credit
Credit Commitments [Line Items]
Credit Commitments	$ 18,036
Standby and Commercial Letters of Credit | Minimum
Credit Commitments [Line Items]
Standby and commercial letters of credit, remaining term (in months)	1 month
Standby and Commercial Letters of Credit | Maximum
Credit Commitments [Line Items]
Standby and commercial letters of credit, remaining term (in months)	24 months