Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details)		3 Months Ended
		Mar. 31, 2019 USD ($) security	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Proceeds from sale of available-for-sale securities		$ 0	$ 0
Unrealized gains (losses) recorded in accumulated other comprehensive loss	[1],[2],[3]	25,800,000	(13,071,000)
Financial instruments pledged as collateral		$ 1,600,000,000		$ 1,900,000,000
Number of available for sale securities whose amortized costs exceeded their fair values | security		186
Available-for-sale Securities, Continuous		$ 23,871,000
Available-for-sale Securities, Continuous Unrealized		9,920,000
Available-for-sale Securities, Continuous		$ 2,042,283,000
Percentage of available-for-sale portfolio		68.00%
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		163
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss		$ 55,196,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		23,280,000
Credit-related OTTI		0	0
Gross unrealized losses related to investment portfolio			$ 79,100,000
Pledged [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Trading securities pledged		$ 1,500,000,000		$ 1,600,000,000

[1] Net of tax expense of $10.1 million and tax benefit of $2.3 million for the three months ended March 31, 2019 and 2018, respectively.

[2] The adoption of ASU 2018-02 on January 1, 2018 resulted in a reclassification of $3.1 million to retained earnings related to cash flow hedges and investment portfolio credit risk.

[3] There were no reclassifications to earnings during the three months ended March 31, 2019 and 2018, respectively.