Income Taxes - Operating loss carryfowards and tax credits (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
U.K. foreign tax credits		$ 9,521	$ 9,116
U.S. refundable AMT credits		1,323	$ 2,652
United Kingdom
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		89,000
U.K. foreign tax credits		9,521
Ireland
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		10,200
Australia
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		22,000
Hong Kong
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		17,600
Denmark
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		400
United States
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	[1],[2]	23,100
U.S. refundable AMT credits		1,323
Operating loss carryforward, portion subject to utilization limits		8,900
Operating loss carryforward, annual utilization limit		600
Watford Holdings Ltd | United States
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		$ 600

[1] Includes $0.6 million net operating loss carryforwards from Watford.

[2] On January 30, 2014, the Company’s U.S. mortgage operations underwent an ownership change for U.S. federal income tax purposes as a result of the Company’s acquisition of the CMG Entities. As a result of this ownership change, a limitation has been imposed upon the utilization of approximately $8.9 million of the Company’s existing U.S. net operating loss carryforwards. Utilization is limited to approximately $0.6 million per year in accordance with Section 382 of the Internal Revenue Code of 1986 as amended (“the Code”).