Derivative and Hedging Activities, Derivative Instruments Not Designated as Hedging Instruments (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Trading assets | Interest rate-related instruments — customer and mirror
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	$ 2,183,687	$ 2,039,323
Fair Value	28,494	33,671
Trading assets | Foreign currency exchange forwards
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	124,851	109,675
Fair Value	2,495	2,002
Trading assets | Commodity contracts
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	457,868	127,582
Fair Value	38,686	16,725
Trading liabilities | Interest rate-related instruments — customer and mirror
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	2,183,687	2,039,323
Fair Value	(28,035)	(33,188)
Trading liabilities | Foreign currency exchange forwards
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	118,094	106,251
Fair Value	(2,339)	(1,943)
Trading liabilities | Commodity contracts
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	457,108	128,368
Fair Value	(37,286)	(15,972)
Other assets | Interest rate lock commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	222,736	285,345
Fair Value	1,538	206
Other assets | Forward commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount		179,600
Fair Value		2,908
Other assets | Purchased options (time deposit)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	31,063	80,554
Fair Value	1,175	2,576
Other liabilities | Forward commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	164,567
Fair Value	(313)
Other liabilities | Written options (time deposit)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	31,063	80,554
Fair Value	$ (1,175)	$ (2,576)