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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassifications included in net income:
Pre-tax	$ 278	$ 123	$ 611	$ 372
Tax (expense) benefit	(67)	(28)	(148)	(88)
Net of tax	211	95	463	284
Gains (losses) on available for sale debt securities | Investment and other income (loss)
Reclassifications included in net income:
Pre-tax	211		477	125
Tax (expense) benefit	(51)		(114)	(30)
Net of tax	160		363	95
Postretirement benefits unrealized gains (losses) | Compensation and benefits
Reclassifications included in net income:
Pre-tax	67	123	134	247
Tax (expense) benefit	(16)	(28)	(34)	(58)
Net of tax	$ 51	$ 95	$ 100	$ 189