Acquisitions - Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Jul. 01, 2019	Dec. 31, 2018
Liabilities:
Goodwill	$ 48,744		$ 47,396
Purchase price		$ 425,600
NTA
Assets:
Investments		542,600
Cash and short-term investments		73,800
Intangible assets		169,800
Other assets		18,300
Liabilities:
Policy reserves		366,800
Policy claims		21,800
Unearned premiums		4,100
Other liabilities		5,500
Total identifiable net assets acquired		406,300
Goodwill		19,300
Goodwill expected to be deductible for tax purposes		$ 17,900
Minimum | NTA
Liabilities:
Acquired finite-lived intangible assets, useful lives	14 years
Maximum | NTA
Liabilities:
Acquired finite-lived intangible assets, useful lives	35 years