Fair Value Disclosures - Summary of Amount by Which Contractual Principal Exceeds Fair Value for Loans and Other Receivables and long-term debt Measured at Fair Value Under Fair Value Option (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Loans and other receivables	$ 752,076	$ 1,325,938
Loans and other receivables on nonaccrual status and/or greater than 90 days past due	159,462	205,746
Long-term debt	32,839	20,202
Loans and other receivables greater than 90 or more days past due	$ 38,700	$ 64,600