Summary of Significant Accounting Policies (Details) - Segment	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Number of reportable segments		1	2
Percentage of decline on cost of securities treated as other-than-temporary impairment		20.00%
Period of decline on the cost of equity securities that will be considered other-than-temporary impairment		6 months
Period of decline on the cost of additional equity securities that will be considered other-than-temporary impairment		1 year
Income Tax Disclosure [Line Items]
Corporate income tax rate		35.00%
Plan [Member]
Income Tax Disclosure [Line Items]
Corporate income tax rate	21.00%