Goodwill and Other Intangible Assets - Change in Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-lived Intangible Assets [Roll Forward]
Balance at the beginning of the year	$ 6,088	$ 7,374	$ 8,789
Additions as a result of acquisitions	18,345	0	0
Amortization	(3,819)	(1,286)	(1,415)
Balance at the end of the year	$ 20,614	$ 6,088	$ 7,374