Nature of Business and Summary of Significant Accounting Policies - Components of Other Current Assets and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Current Assets and Liabilities [Line Items]
Other	$ 5,781	$ 8,755
Total other current assets	58,126	33,578
Settlement payables	48,953	24,016
Accrued interest	7,291	7,356
Vendor financed licenses	1,862	9,213
Royalties payable	9,264	7,197
Other	35,534	31,059
Total other current liabilities	102,904	78,841
Settlement deposits [Member]
Other Current Assets and Liabilities [Line Items]
Other assets settlement	22,282	10,496
Settlement receivables [Member]
Other Current Assets and Liabilities [Line Items]
Other assets settlement	$ 30,063	$ 14,327