Investment Securities (Significant Unobservable Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
DavidShield & PassportCard | Standard Poors NR Rating | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 75.0
Unobservable Input	0.18
DavidShield & PassportCard | Standard Poors NR Rating | Exit Revenue Multiple
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Input	1
PassportCard | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value		$ 21.0
Unobservable Input		0.25
PassportCard | Standard Poors NR Rating | Exit Revenue Multiple
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Input		1
Compare.com | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value		$ 22.1
Unobservable Input		0.35
Compare.com | Standard Poors NR Rating | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 16.9
Unobservable Input	0.22
Compare.com | Standard Poors NR Rating | Exit Revenue Multiple
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Input	2.75	1.75
YOUSURE Tarifvergleich GmbH “durchblicker” | Standard Poors NR Rating | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 15.5	$ 11.3
Unobservable Input	0.23	0.21
YOUSURE Tarifvergleich GmbH “durchblicker” | Standard Poors NR Rating | Exit Revenue Multiple
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Input	2.25	1.75
Captricity | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value		$ 14.5
Unobservable Input		.30
Captricity | Standard Poors NR Rating | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 14.5
Unobservable Input	0.23
Captricity | Standard Poors NR Rating | Exit Revenue Multiple
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Input	3.75	3.50
Galvanic | Multiple of EBITDA
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value		$ 0.6
Unobservable Input		6
Galvanic | Standard Poors NR Rating | Multiple of EBITDA
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 3.1
Unobservable Input	6
Private debt instrument | Standard Poors NR Rating | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value	$ 10.0
Unobservable Input	0.0962
OneTitle | Recent transaction
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, fair value		$ 3.6
Unobservable Input		2.521