Goodwill and Other Intangible Assets - Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Total	$ 117,823	$ 127,340
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	146,355	148,679
Accumulated amortization	(42,965)	(36,871)
Total	103,390	111,808	$ 79,807
Books of Business Intangible
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	19,938	20,350
Accumulated amortization	(5,505)	(4,818)
Total	$ 14,433	$ 15,532	$ 11,527