Subsequent Events - Additional Information (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 28, 2017	Apr. 15, 2017	Mar. 31, 2017	Dec. 31, 2016
Subsequent Events [Line Items]
Long-term debt			$ 149,473	$ 149,352
Subsequent Event [Member]
Subsequent Events [Line Items]
Date of announcement of dividend	Apr. 28, 2017
Date of payment of dividend	May 26, 2017
Date of record of dividend	May 12, 2017
Class A Stock | Subsequent Event [Member]
Subsequent Events [Line Items]
Quarterly dividend payable amount per share	$ 0.11
Class B Stock | Subsequent Event [Member]
Subsequent Events [Line Items]
Quarterly dividend payable amount per share	$ 0.11
The Notes [Member] | Subsequent Event [Member]
Subsequent Events [Line Items]
Debt instrument, repurchase amount		$ 30,000
Percent of principal amount to be repurchased		100.00%
Long-term debt		$ 120,000