Investment Securities (Visa Class B Restricted Shares Narrative) (Details 8) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)
Net Investment Income [Line Items]
Gain on Sale of Investment Securities | $	$ 0	$ 0	$ 12,467	$ 11,180
Visa Class B Restricted Securities
Net Investment Income [Line Items]
Conversion Ratio to Class A shares	1.6483		1.6483
Gain on Sale of Investment Securities | $	$ 12,500
Sale of investment securities, shares	90,000
Equity securities remaining, shares	90,914		90,914
Visa Class A Unrestricted Securities
Net Investment Income [Line Items]
Equity securities remaining, shares	149,854		149,854