Receivables - Additional Information (Detail) - USD ($)	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables past due or deemed uncollectible	$ 38,732,000		$ 22,212,000
Interest-bearing financing fee receivables	57,315,000		76,133,000
Allowance for doubtful accounts receivables	25,094,000	$ 29,662,000	16,386,000	$ 13,569,000	$ 11,230,000	$ 12,882,000
Aggregate carrying amount of non-interest bearing receivables	597,424,000		562,149,000
Financing Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts receivables	$ 0		$ 0