Derivatives (Derivatives Associated With Interest Rate Risk Management Activities) (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Term borrowings		$ 1,341,186,000	$ 1,491,138,000	$ 1,341,186,000	$ 1,491,138,000	$ 1,880,105,000
Customer Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional		1,670,717,000	1,731,047,000	1,670,717,000	1,731,047,000
Assets		82,905,000	69,878,000	82,905,000	69,878,000
Liabilities		1,512,000	5,778,000	1,512,000	5,778,000
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]	790,321,000	742,065,000	790,321,000	742,065,000
Assets	[1]	34,507,000	25,039,000	34,507,000	25,039,000
Liabilities	[1]	210,000	1,128,000	210,000	1,128,000
Gains/(Losses)	[1]	10,558,000	(3,235,000)	8,643,000	(1,166,000)
Offsetting Upstream Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional		1,670,717,000	1,731,047,000	1,670,717,000	1,731,047,000
Assets		1,512,000	5,778,000	1,512,000	5,778,000
Liabilities		82,905,000	69,878,000	82,905,000	69,878,000
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]	790,321,000	742,065,000	790,321,000	742,065,000
Assets	[1]	210,000	1,128,000	210,000	1,128,000
Liabilities	[1]	35,007,000	25,539,000	35,007,000	25,539,000
Gains/(Losses)	[1]	(10,558,000)	3,235,000	(8,643,000)	1,166,000
Interest Rate Swap [Member] | Debt [Member] | Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional	[2]	1,150,000,000	1,254,000,000	1,150,000,000	1,254,000,000
Assets	[2]	16,960,000	32,711,000	16,960,000	32,711,000
Liabilities	[2]		9,787,000		9,787,000
Gains/(Losses)	[2]	3,247,000	(7,074,000)	(6,593,000)	(10,313,000)
Long Term Debt [Member] | Debt [Member] | Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Term borrowings	[2],[3]	1,150,000,000	1,254,000,000	1,150,000,000	1,254,000,000
Gains/(Losses) related to term borrowings	[2],[4]	$ (3,167,000)	$ 7,074,000	$ 6,645,000	$ 10,313,000

[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.