Stockholders' Equity - Reclassifications from accumulated other comprehensive income (loss) and included in net income (Details) - Reclassifications from accumulated other comprehensive income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassifications included in net income:
Pre-tax	$ 333	$ 249
Tax (expense) benefit	(82)	(60)
Net of tax	251	189
Gains (losses) on available for sale debt securities | Investment and other income (loss)
Reclassifications included in net income:
Pre-tax	266	125
Tax (expense) benefit	(64)	(30)
Net of tax	202	95
Postretirement benefits unrealized gains (losses) | Compensation and benefits
Reclassifications included in net income:
Pre-tax	67	124
Tax (expense) benefit	(18)	(30)
Net of tax	$ 49	$ 94