Derivative Instruments and Hedging Activities - Balance Sheet Disclosures (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Interest rate swaps
Derivative [Line Items]
Other Assets	$ 0	$ 0
Other Liabilities	59,411	22,907
Derivatives designated as hedging instruments
Derivative [Line Items]
Other Assets	0	0
Other Liabilities	2,231	374
Notional Amount	262,346	339,536
Derivatives designated as hedging instruments | Cash flow hedge interest rate swaps | Interest rate swaps
Derivative [Line Items]
Other Assets	0	0
Other Liabilities	1,941	27
Notional Amount	255,000	332,000
Derivatives designated as hedging instruments | Fair value hedge interest rate swaps | Interest rate swaps
Derivative [Line Items]
Other Assets	0	0
Other Liabilities	290	347
Notional Amount	7,346	7,536
Derivatives not designated as hedging instruments
Derivative [Line Items]
Other Assets	217,035	48,979
Other Liabilities	57,856	23,307
Notional Amount	4,094,099	3,495,825
Derivatives not designated as hedging instruments | Interest rate swaps
Derivative [Line Items]
Other Assets	216,340	48,642
Other Liabilities	57,180	22,533
Notional Amount	3,840,078	3,390,578
Derivatives not designated as hedging instruments | Mortgage banking derivatives
Derivative [Line Items]
Other Assets	695	337
Other Liabilities	676	774
Notional Amount	$ 254,021	$ 105,247