Capital Stock (Dividends) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Capital Stock
Dividends (in dollars per share)	$ 0.50	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.50	$ 1.80
Amount (in thousands)	$ 8,245	$ 7,956	$ 7,000	$ 7,425	$ 7,839	$ 8,245	$ 30,220