Stockholders' Equity Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Dividends declared	$ 503	$ 2,961
Class A
Class of Stock [Line Items]
Common Stock, Dividends, Per Share, Cash Paid		$ 0.0588	$ 0.014
Retained Earnings
Class of Stock [Line Items]
Dividends declared	$ 503	$ 2,961	$ 500