Goodwill and other intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 158,057	$ 72,334	$ 158,057	$ 72,334	$ 112,739	$ 72,334
Other Intangible Assets, Net	16,231	0	16,231	0	6,971	0
Goodwill, Acquired During Period			45,318	0	40,405
Indefinite-lived Intangible Assets Acquired			10,251	0
Acquired goodwill and intangibles			55,569	0
Amortization of Intangible Assets	702	0	991	0
Finite-lived Intangible Assets Acquired	16,500		16,500		6,249
Indefinite-lived Intangible Assets Acquired	1,300		1,300		1,300
Finite-Lived Intangible Assets, Accumulated Amortization	1,569		1,569		578
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	1,482		1,482
Finite-Lived Intangible Assets, Amortization Expense, Year Two	2,502		2,502
Finite-Lived Intangible Assets, Amortization Expense, Year Three	2,040		2,040
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,725		1,725
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1,548		1,548
Intangible Assets, Gross (Excluding Goodwill)	17,800		17,800		7,549
Intangible Assets, Net (Including Goodwill)	174,288	$ 72,334	174,288	$ 72,334	119,710	$ 72,334
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	1,569		1,569		578
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 0		$ 0		$ 0