Reserve for Losses and Loss Adjustment Expenses - Schedule of incurred loss and allocated loss adjustment expense development (Details) $ in Thousands	Dec. 31, 2016 USD ($) default_loan	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and LAE	$ 28,142	$ 17,760	$ 8,427
Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	37,582
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	9,440
All outstanding liabilities before 2010, net of reinsurance	0
Reserve for losses and LAE	28,142
2010 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	0	0	0	$ 0	$ 0	$ 0	$ 0
Total of IBNR plus Expected Development on Reported Defaults	$ 0
Cumulative Number of Reported Defaults | default_loan	0
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 0	0	0	0	0	0	$ 0
2011 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	0	0	0	0	0	57
Total of IBNR plus Expected Development on Reported Defaults	$ 0
Cumulative Number of Reported Defaults | default_loan	1
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 0	0	0	0	0	$ 0
2012 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	748	781	814	858	1,523
Total of IBNR plus Expected Development on Reported Defaults	$ 6
Cumulative Number of Reported Defaults | default_loan	19
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 665	665	659	535	$ 24
2013 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	1,997	2,008	2,461	2,986
Total of IBNR plus Expected Development on Reported Defaults	$ 16
Cumulative Number of Reported Defaults | default_loan	52
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 1,775	1,501	928	$ 239
2014 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	3,323	4,312	6,877
Total of IBNR plus Expected Development on Reported Defaults	$ 60
Cumulative Number of Reported Defaults | default_loan	104
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 2,463	1,587	$ 138
2015 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	9,625	14,956
Total of IBNR plus Expected Development on Reported Defaults	$ 416
Cumulative Number of Reported Defaults | default_loan	300
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 3,610	$ 544
2016 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Loss and Allocated LAE, For the Years Ended December 31,	21,889
Total of IBNR plus Expected Development on Reported Defaults	$ 1,434
Cumulative Number of Reported Defaults | default_loan	1,559
Cumulative Paid Losses and Allocated LAE For the Years Ended December 31,	$ 927