DISCONTINUED OPERATIONS - Summary of Carrying Amounts of Major Classes of Assets and Liabilities and Pretax Profit or Loss Associated with Disposed Travel and Entertainment Segment (Details) - USD ($) $ in Thousands	4 Months Ended	12 Months Ended
	May 15, 2019	Dec. 31, 2019	Dec. 31, 2018
Major classes of assets and liabilities
Current assets		$ 0	$ 28,966
Current liabilities		0	41,648
Line items constituting pretax profit or loss
Loss from discontinued operations		$ (2,610)	(2,993)
VDC Transaction | Discontinued Operations, Disposed of by Sale
Major classes of assets and liabilities
Cash and cash equivalents (including restricted cash)	$ 18,011
Other current assets	4,753
Current assets	22,764
Property and equipment, net	7,331
Goodwill and other intangibles, net	28,977
Other assets	1,856
Total assets	60,928
Accounts payable, accrued expense and other current liabilities	22,749
Deferred merchant booking	7,358
Contract liability	5,381
Current liabilities	35,488
Other liabilities	1,938
Total liabilities	37,426
Line items constituting pretax profit or loss
Revenue	27,432
Cost of revenue (excluding depreciation and amortization)	4,016
Selling, general and administrative	18,383
Technology and development	3,280
Depreciation, amortization and impairments	8,007
Other operating expense	384
Other expense (income) and loss (gain), net	(3,814)
Loss from discontinued operations before income taxes	(2,824)
Benefit from income taxes	214
Loss from discontinued operations	$ (2,610)
VDC Transaction | Discontinued Operations, Held-for-sale
Major classes of assets and liabilities
Cash and cash equivalents (including restricted cash)			24,138
Other current assets			4,828
Current assets			28,966
Property and equipment, net			8,495
Goodwill and other intangibles, net			35,434
Other assets			194
Total assets			73,089
Accounts payable, accrued expense and other current liabilities			33,053
Deferred merchant booking			4,664
Contract liability			3,931
Current liabilities			41,648
Other liabilities			34
Total liabilities			41,682
Line items constituting pretax profit or loss
Revenue			69,057
Cost of revenue (excluding depreciation and amortization)			11,725
Selling, general and administrative			38,906
Technology and development			8,939
Depreciation, amortization and impairments			8,786
Other operating expense			954
Other expense (income) and loss (gain), net			3,267
Loss from discontinued operations before income taxes			(3,520)
Benefit from income taxes			527
Loss from discontinued operations			$ (2,993)