Derivatives (Derivatives Associated With Interest Rate Risk Management Activities) (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Term borrowings		$ 1,557,647,000	$ 1,501,209,000	$ 1,557,647,000	$ 1,501,209,000	$ 1,880,105,000
Customer Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional		1,640,844,000	1,760,032,000	1,640,844,000	1,760,032,000
Assets		66,078,000	80,710,000	66,078,000	80,710,000
Liabilities		3,285,000	4,948,000	3,285,000	4,948,000
Customer Interest Rate Contracts [Member] | Customer Interest Rate Contracts Hedging [Member] | Hedging Instruments And Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	[1]	744,167,000	759,266,000	744,167,000	759,266,000
Assets	[1]	24,148,000	28,143,000	24,148,000	28,143,000
Liabilities	[1]	409,000	997,000	409,000	997,000
Gains/(Losses)	[1]	(6,158,000)	2,714,000	(1,915,000)	2,069,000
Offsetting Upstream Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional		1,640,844,000	1,760,032,000	1,640,844,000	1,760,032,000
Assets		3,285,000	4,948,000	3,285,000	4,948,000
Liabilities		66,078,000	80,710,000	66,078,000	80,710,000
Offsetting Upstream Interest Rate Contracts [Member] | Customer Interest Rate Contracts Hedging [Member] | Hedging Instruments And Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	[1]	744,167,000	775,204,000	744,167,000	775,204,000
Assets	[1]	409,000	997,000	409,000	997,000
Liabilities	[1]	24,648,000	28,643,000	24,648,000	28,643,000
Gains/(Losses)	[1]	6,158,000	(2,714,000)	1,915,000	(2,069,000)
Interest Rate Swap [Member] | Debt [Member] | Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	[2]	1,350,000,000	1,254,000,000	1,350,000,000	1,254,000,000
Assets	[2]	15,954,000	42,121,000	15,954,000	42,121,000
Liabilities	[2]	5,131,000	12,095,000	5,131,000	12,095,000
Gains/(Losses)	[2]	(10,810,000)	(3,628,000)	(9,840,000)	(3,239,000)
Long Term Debt [Member] | Debt [Member] | Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Term borrowings	[2],[3]	1,350,000,000	1,254,000,000	1,350,000,000	1,254,000,000
Gains/(Losses) related to term borrowings	[2],[4]	$ 10,735,000	$ 3,628,000	$ 9,812,000	$ 3,239,000

[1] Gains/losses included in the All o ther expense section of the Consolidated Condensed Statements of Income.

[2] Gains/losses included in the All other income and commissions section of the Consolidated Condensed Statements of Income.

[3] Represents par value of term borrowings being hedged.

[4] Represents gains and losses attributable to changes in fair value due to interest rate risk as designated in ASC 815-20 hedging relationships.