Fair Value Measurement (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net gain recognized on equity securities sold during the period	$ 81,853		$ 0	$ 81,853	$ 0
Unrealized gains (losses) arising during the period	17,240	$ 17,200	(1,513)	23,804	(3,196)
Change in unrealized gains on junior subordinated debentures carried at fair value, net of taxes	12,781		(1,127)	17,701	(2,380)
Net gain (loss) representing the change in fair value in earnings	$ 4,900		$ 5,700	$ 7,700	$ 5,400
Visa Incorporation [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Company Stock Owned Shares	486,346			486,346
Class B common Stock of Visa Inc
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net gain recognized on equity securities sold during the period				$ 81,900

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount, after tax, before reclassification adjustment, of unrealized gain (loss) from increase (decrease) in instrument-specific credit risk of financial liability measured under fair value option.

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