Goodwill and Other Intangible Assets - Estimated Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Goodwill and other intangibles assets
Net carrying amount	$ 61,593	$ 32,873
Estimated amortization expense:
Net carrying amount	61,593	32,873
Core deposit intangible assets
Goodwill and other intangibles assets
Gross carrying amount	90,256
Accumulated amortization	39,156
Net carrying amount	51,100	31,836
Estimated amortization expense:
2020	7,753
2021	7,259
2022	6,749
2023	6,225
2024	5,686
Thereafter	17,428
Net carrying amount	51,100	31,836
Customer relationship intangible assets
Goodwill and other intangibles assets
Gross carrying amount	24,208
Accumulated amortization	13,715
Net carrying amount	10,493	1,037
Estimated amortization expense:
2020	2,188
2021	1,926
2022	1,664
2023	1,403
2024	1,141
Thereafter	2,171
Net carrying amount	$ 10,493	$ 1,037