Other Assets - Summary of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets [Abstract]
Debt issue costs, net	$ 4,793	$ 7,093
Equity investments	520,058	288,398
Other corporate assets	115,416	117,827
Prepaids and other assets	61,757	55,176
Total other assets	$ 702,024	$ 468,494