Unpaid Loss and Loss Adjustment Expenses Cumulative paid loss and allocated loss adjustment expenses, net of reinsurance (Details) - USD ($)

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Liability for Claims and Claims Adjustment Expense [Line Items]

Balance at beginning of period, net

$ 2,028,000

$ 1,178,000

Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

138,641,000

Balance at beginning of period, net

680,000

479,000

Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

33,715,000

Balance at beginning of period, net

756,000

521,000

Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

18,177

Balance at beginning of period, net

2,000

Accident Year 2007 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

40,085,000

$ 40,087,000

$ 40,089,000

$ 40,072,000

$ 39,600,000

$ 38,796,000

$ 36,390,000

$ 32,436,000

$ 18,742,000

Accident Year 2007 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

7,585,000

7,595,000

7,606,000

7,562,000

7,418,000

6,604,000

5,753,000

3,297,000

Accident Year 2007 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

6,482

6,481

6,480

6,487

6,489

6,499

6,505

6,463

$ 6,221

Accident Year 2008 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

53,570,000

53,518,000

53,484,000

53,451,000

52,889,000

51,944,000

50,591,000

46,356,000

25,659,000

Accident Year 2008 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

9,136,000

9,132,000

9,142,000

9,149,000

9,069,000

8,922,000

8,658,000

7,716,000

4,177,000

Accident Year 2008 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

5,538

5,537

5,526

5,548

5,583

$ 5,155

Accident Year 2009 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

27,677,000

27,479,000

27,431,000

27,378,000

27,023,000

26,599,000

25,296,000

18,456,000

Accident Year 2009 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

8,767,000

8,765,000

8,747,000

8,638,000

8,533,000

8,326,000

7,926,000

5,005,000

Accident Year 2009 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

3,261

3,269

3,267

3,266

3,270

3,268

$ 2,971

Accident Year 2010 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

12,738,000

12,635,000

12,618,000

12,530,000

12,284,000

11,724,000

7,060,000

Accident Year 2010 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

7,943,000

7,681,000

7,457,000

7,150,000

7,028,000

6,607,000

5,034,000

Accident Year 2010 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

1,908

2,018

2,017

2,016

2,006

1,951

$ 1,783

Accident Year 2011 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

4,571,000

4,562,000

4,496,000

4,437,000

4,277,000

3,575,000

Accident Year 2011 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

284,000

358,000

352,000

299,000

Accident Year 2011 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

988

1,002

1,001

1,015

$ 1,050

Accident Year 2012 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2012 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2012 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

$ 0

Accident Year 2013 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2013 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2013 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

$ 0

Accident Year 2014 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2014 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2014 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

$ 0

Accident Year 2015 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2015 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2015 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2016 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2016 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year 2016 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

Accident Year Prior to 2007 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

5,000

Accident Year Prior to 2007 [Member] | Non-standard automobile [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

$ 410,000

Accident Year Prior to 2007 [Member] | Auto physical damage [Member]

Liability for Claims and Claims Adjustment Expense [Line Items]

Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid

$ 0