Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2016 USD ($) security	Mar. 31, 2015 USD ($)	Dec. 31, 2015 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]	(1,028)	6,945
Financial instruments pledged as collateral		2,100,000		$ 1,400,000
Trading securities pledged		$ 1,300,000		1,100,000
Number of available for sale securities whose amortized costs exceeded their fair values | security		98
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		$ 20,768
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		4,956
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		$ 1,277,061
Percentage of available-for-sale portfolio		60.10%
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		37
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss		$ 9,367
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		2,087
Credit-related OTTI		0	$ 0
Gross unrealized losses related to investment portfolio	[3]	20,768		$ 13,298
Available-for-sale and Held-to-maturity Securities [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Gross unrealized losses related to investment portfolio		$ 30,000

[1] Net of tax benefit of $4.7 million and tax expense of $2.4 million for the three months ended March 31, 2016 and 2015, respectively.

[2] There were no reclassifications to earnings of realized gains during the three months ended March 31, 2016 and 2015, respectively

[3] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive loss.