Basis of Condensed Consolidated Financial Statements (Narrative) (Details) $ / shares in Units, $ in Thousands	1 Months Ended					3 Months Ended
	Feb. 28, 2021 USD ($) $ / shares	Nov. 30, 2020 director investment	Oct. 31, 2020 USD ($)	Jul. 31, 2020 director $ / shares	Jan. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) businessDay segment investment $ / shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) investment $ / shares	Sep. 14, 2020 $ / shares	Jun. 26, 2020 $ / shares	Dec. 31, 2019 USD ($) $ / shares
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Common stock, par value (in dollars per share) | $ / shares						$ 0.00001		$ 0.00001
Number of directors to be replaced | director				9
Number of directors replaced | director		3
Number of directors appointed | investment		3
Number of reportable segments | segment						2
Loss from sale of discontinued operations, net of tax			$ 2,700			$ (5,288)	$ 0
Number of impaired investments | investment						1		1
Dividends received from investments in affiliates						$ 0	185
Operating lease impairment loss						0	0
Finance lease impairment loss						0	0
Dividends payable (in usd per share) | $ / shares											$ 0.22
Increase in common stock dividend declared				50.00%
Dividends declared (in usd per share) | $ / shares				$ 0.33
Tax escrow deposits						7,400,000		$ 500,000
Reserves incorrect disposition of assets						27,800		29,600
Stockholders' equity						756,085	926,998	723,262			$ 951,210
Retained Earnings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Stockholders' equity						914,622	1,057,692	893,404			1,006,992
Cumulative Effect, Period of Adoption, Adjustment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Stockholders' equity											16,827
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Stockholders' equity											$ 16,827
Discontinued Operations, Disposed of by Sale | Rental Property Solutions
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Loss from sale of discontinued operations, net of tax			2,700			(5,300)
Consideration received	$ 51,200		$ 9,000
Senator Investment Group, LP and Cannae Holdings, Inc.
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Share price (in usd per share) | $ / shares									$ 66.00	$ 65.00
Increase to original offer (in usd per share) | $ / shares									$ 1.00
Costs accrued						11,400
Accounts Payable and Accrued Liabilities
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Reserves incorrect disposition of assets						$ 11,700		$ 11,400
Minimum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Period that escrow deposits are held (in business days) | businessDay						2
Maximum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Period that escrow deposits are held (in business days) | businessDay						5
Celestial-Saturn Parent Inc.
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 0.00001
Share price (in usd per share) | $ / shares	$ 80.00
Failure to consummate the merger termination fee	$ 330,000
Termination fee payable	$ 165,000
Location, Inc
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Remaining equity interest acquired					66.00%
Consideration transferred					$ 11,500
Investment balance					$ 5,600
Dividends received from investments in affiliates							$ 700
Location, Inc | PIRM
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Ownership percentage					34.00%
Step-up gain					$ 600
Ten Largest Clients | Sales Revenue, Net | Customer Concentration Risk
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Concentration risk, percentage						40.00%	30.00%