XML 118 R104.htm IDEA: XBRL DOCUMENT

Federal Income Taxes - Tax Status of Dividends (Details) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Total (in dollars per share)	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 0.26	$ 1.09	$ 1.05	$ 1.16
Characterization Of Distributions For Federal Income Tax Purposes
Income Tax Contingency [Line Items]
Qualified dividend (in dollars per share)									0	0	0
Capital gain (in dollars per share)									0	0.23	0.39
Total (in dollars per share)									$ 0.87	$ 1.05	$ 1.16
Qualified dividend									0.00%	0.00%	0.00%
Capital gain									0.00%	22.00%	34.00%
Total									100.00%	100.00%	100.00%
Characterization Of Distributions For Federal Income Tax Purposes \| Non-Section 199A
Income Tax Contingency [Line Items]
Ordinary income (in dollars per share)									$ 0	$ 0.82	$ 0.77
Ordinary income									0.00%	78.00%	66.00%
Characterization Of Distributions For Federal Income Tax Purposes \| Section 199A
Income Tax Contingency [Line Items]
Ordinary income (in dollars per share)									$ 0.87	$ 0	$ 0
Ordinary income									100.00%	0.00%	0.00%