Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Total intangible assets	$ 35,797	$ 40,211
Core deposit intangible assets
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	59,143	59,143
Accumulated amortization	23,396	18,932
Total intangible assets	35,747	40,211
Non-compete intangible assets
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Total intangible assets	$ 50	$ 0