Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts receivable, allowances	$ 997	$ 684
Borrowings under credit facilities, stated value	$ 1,293,405	$ 1,279,188
Class A common stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	500,000,000	500,000,000
Common stock, issued shares	48,091,707	47,421,315
Common stock, outstanding shares	48,091,707	47,421,315
Class B common stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	500,000,000	500,000,000
Common stock, issued shares	21,496,103	22,075,749
Common stock, outstanding shares	21,496,103	22,075,749