Other Comprehensive (Loss) Income (Reclassifications Out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Compensation and employee benefits	$ 29,200	$ 28,990	$ 60,395	$ 57,359
Income tax expense	3,715	8,802	8,972	16,491
Net income	(14,311)	(24,393)	(29,242)	(55,283)
Reclassification adjustment | Post-retirement obligations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Compensation and employee benefits	112	47	224	94
Income tax expense	(29)	(13)	(58)	(26)
Net income	$ 83	$ 34	$ 166	$ 68