Income Taxes - Reconciliation of Federal Statutory Income Tax Rate to Effective Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	21.00%	21.00%	35.00%
State and local income taxes, net of federal income taxes	3.40%	3.80%	3.10%
Unrecognized tax benefits adjustments	(1.00%)	(1.00%)	(1.90%)
Foreign operations tax differential	(0.50%)	0.30%	(1.40%)
Non-deductible (gains) losses on investments	(1.60%)	0.20%	0.20%
Non-taxable (gains) losses on investments	0.90%	0.10%	(0.20%)
Tax Act	0.00%	(0.10%)	8.00%
Other	1.00%	(1.20%)	(0.30%)
Effective income tax rate	23.20%	23.10%	42.50%