BUSINESS ACQUISITIONS (Details)								3 Months Ended									6 Months Ended	12 Months Ended
	Jan. 10, 2019 USD ($)	Oct. 31, 2018 USD ($) payment	Jul. 23, 2018 USD ($)	Jun. 11, 2018 USD ($) payment	Sep. 19, 2017 USD ($) payment	Jun. 20, 2017 USD ($) shares	Jun. 14, 2017 USD ($) payment	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill									$ 420,139,000			$ 348,347,000						$ 420,139,000	$ 348,347,000	$ 113,368,000
Acquisition related costs																		600,000	6,900,000	1,000,000.0
Current contingent consideration									23,400,000									12,500,000	21,912,000	0
Contingent consideration payments									13,900,000									$ 21,275,000	27,588,000	0
Contingent consideration payment, operating									9,500,000
Document Period End Date																		Dec. 31, 2019
Change in fair value of contingent consideration											$ 14,400,000	6,800,000						$ 28,402,000	10,788,000	23,931,000
Contingent consideration arrangements, after tax contingent consideration expense																		21,500,000	7,200,000	1,600,000
Current contingent consideration									9,028,000			11,080,000						9,028,000	11,080,000
Stock granted, net of forfeitures						$ 10,000,000.0
ValuePenguin
Business Acquisition [Line Items]
Acquisition purchase consideration	$ 106,100,000
Total purchase price	106,200,000																	106,232,000
Working capital adjustment	100,000
Goodwill	71,700,000								71,739,000									71,739,000
Revenue of acquirees since acquisition date																		19,800,000
Earnings of acquiree since acquisition date																	$ 3,100,000
Acquisition related costs																		100,000
QuoteWizard
Business Acquisition [Line Items]
Acquisition purchase consideration		$ 299,900,000
Total purchase price		313,400,000																313,355,000
Working capital adjustment		400,000
Goodwill		182,900,000							182,896,000									182,896,000
Acquisition related costs																		4,800,000
Cash on hand		$ 174,900,000
Number of payments | payment		3
Contingent consideration on acquisition date		$ 13,900,000							24,400,000									24,400,000
Change in fair value of contingent consideration																		27,100,000	6,800,000
Contingent consideration arrangements, after tax contingent consideration expense																			4,900,000	5,900,000
Student Loan Hero
Business Acquisition [Line Items]
Acquisition purchase consideration			$ 60,700,000
Total purchase price			60,400,000															60,418,000
Working capital adjustment			2,000,000.0
Goodwill			40,900,000						40,856,000									40,856,000
Acquisition related costs																		500,000
Severance costs			$ 2,300,000
Ovation
Business Acquisition [Line Items]
Acquisition purchase consideration				$ 12,200,000
Total purchase price				17,900,000														17,871,000
Working capital adjustment				100,000
Goodwill				$ 11,300,000					11,280,000									11,280,000
Acquisition related costs																		400,000
Number of payments | payment				2
Contingent consideration on acquisition date				$ 5,800,000
Contingent consideration payments									4,400,000
Change in fair value of contingent consideration																			1,600,000
Current contingent consideration									3,100,000									3,100,000
SnapCap
Business Acquisition [Line Items]
Acquisition purchase consideration					$ 11,900,000													0	10,000	11,886,000
Total purchase price					18,200,000														18,226,000
Goodwill					13,700,000							13,738,000							13,738,000
Acquisition related costs																				300,000
Contingent consideration on acquisition date					$ 6,300,000
Contingent consideration payments											3,000,000.0
Change in fair value of contingent consideration																		2,200,000	(300,000)	700,000
Current contingent consideration									5,900,000									5,900,000
Number of contingent consideration payments | payment					3
Earnout Payment
Business Acquisition [Line Items]
Contingent consideration range, maximum					$ 3,000,000.0
MagnifyMoney
Business Acquisition [Line Items]
Acquisition purchase consideration						29,600,000
Total purchase price																			29,592,000
Goodwill						23,800,000						23,784,000							23,784,000
Acquisition related costs																				400,000
Option to acquire a foreign affiliate						$ 500,000
Option to acquire a foreign affiliate, window						3 years
DepositAccounts
Business Acquisition [Line Items]
Acquisition purchase consideration							$ 24,000,000.0											0	0	25,000,000
Total purchase price							29,000,000.0												28,989,000
Goodwill							19,400,000					19,389,000							19,389,000
Acquisition related costs																				300,000
Contingent consideration range, maximum							9,000,000.0
Contingent consideration on acquisition date							$ 5,000,000.0		$ 0									0
Contingent consideration payments											$ 1,000,000.0	$ 1,000,000.0	$ 1,000,000	$ 1,000,000	$ 1,000,000	$ 1,000,000.0
Contingent consideration payment, operating										$ 2,000,000.0
Change in fair value of contingent consideration																		$ (1,000,000.0)	$ 2,000,000.0	$ 2,000,000
Number of contingent consideration payments | payment							7
Contingent consideration, individual payments based on specified increases in federal funds interest rates							$ 1,000,000.0
Contingent consideration, one-time performance payment							$ 2,000,000.0
Earnout Payment | QuoteWizard
Business Acquisition [Line Items]
Contingent consideration range, minimum		0
Contingent consideration range, maximum		23,400,000
Earnout Payment | Ovation
Business Acquisition [Line Items]
Contingent consideration range, minimum				0
Contingent consideration range, maximum				$ 4,400,000
Earnout Payment | SnapCap
Business Acquisition [Line Items]
Contingent consideration range, minimum					$ 0
Two Key Employees | MagnifyMoney
Business Acquisition [Line Items]
Granted (in shares) | shares						38,468
Third Key Employee | MagnifyMoney
Business Acquisition [Line Items]
Granted (in shares) | shares																		19,234
Revolving Credit Facility | ValuePenguin
Business Acquisition [Line Items]
Proceeds from revolving credit facility	$ 90,000,000.0
Revolving Credit Facility | QuoteWizard
Business Acquisition [Line Items]
Proceeds from revolving credit facility		$ 125,000,000.0
RSUs
Business Acquisition [Line Items]
Granted (in shares) | shares																		62,248
Subsequent Event [Member] | SnapCap
Business Acquisition [Line Items]
Contingent consideration payments								$ 3,000,000.0