Compensation Plans - Reclassifications Out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Noninterest income	$ 14,418	$ 13,564	$ 11,964	$ 9,230	$ 10,702	$ 8,410	$ 9,693	$ 9,542	$ 49,176	$ 38,347	$ 34,394
Net interest income	61,613	63,046	61,715	52,343	50,593	48,093	47,048	46,171	238,717	191,905	177,304
Income before income tax expense	36,336	36,538	22,903	20,259	28,428	24,318	27,132	24,699	116,036	104,577	86,517
Income tax expense	7,246	7,469	4,479	4,103	4,899	1,802	4,881	3,778	23,297	15,360	38,327
Net income	$ 29,090	$ 29,069	$ 18,424	$ 16,156	$ 23,529	$ 22,516	$ 22,251	$ 20,921	92,739	89,217	48,190
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income before income tax expense									(182)	9	22
Income tax expense									45	(2)	(9)
Net income									(137)	7	13
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Noninterest income									(49)	9	22
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net interest income									$ (133)	$ 0	$ 0