Other Assets and Accrued Liabilities - Long-Term Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Broadband contract acquisition and fulfillment costs	$ 10,494	$ 10,252
Prepaid expenses and other	4,504	1,398
Deferred charges and other assets	$ 14,998	$ 11,650