Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Summary of changes in accumulated other comprehensive loss
Beginning Balance	$ 533,111	$ 592,584
Total other comprehensive income, net of tax	606	629
Ending Balance	530,320	581,196
Unrealized gain on available for sale securities
Summary of changes in accumulated other comprehensive loss
Beginning Balance	(674)
Other comprehensive loss before reclassifications	604
Amounts reclassified from accumulated other comprehensive loss	2
Total other comprehensive income, net of tax	606	$ 629
Ending Balance	$ (68)