Capital Stock (Dividends) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017
Equity [Abstract]
Dividends (in dollars per share)	$ 0.35	$ 0.35	$ 0.35	$ 0.00	$ 1.05
Amount (in thousands)	$ 7,606	$ 8,200	$ 8,563	$ 0	$ 24,369