Derivatives and Balance Sheet Offsetting - Fair value of derivatives & classifications table (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Designated as Hedging Instrument [Member] | Interest rate collar [Domain]
Derivative [Line Items]
Fair value of asset derivative instruments	$ 35,668	$ 14,727
Designated as Hedging Instrument [Member] | Other Assets [Member] | Interest rate collar [Domain]
Derivative [Line Items]
Fair value of asset derivative instruments	35,668	14,727
Designated as Hedging Instrument [Member] | Other Liabilities [Member] | Interest rate collar [Domain]
Derivative [Line Items]
Fair value of liability derivative instruments	0	0
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Fair value of asset derivative instruments	53,202	19,144
Fair value of liability derivative instruments	53,677	19,145
Not Designated as Hedging Instrument [Member] | Other Assets [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Fair value of asset derivative instruments	53,202	19,144
Not Designated as Hedging Instrument [Member] | Other Liabilities [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Fair value of liability derivative instruments	$ 53,677	$ 19,145