Reserves for Unpaid Losses and Loss Adjustment Expenses (Incurred and Paid Claims Development - Programs) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development	$ 60,900	$ 5,953
Incurred claims and claim adjustment expenses related to current year	301,265	250,075
Total incurred	362,165	256,028
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	192,335	232,345
Paid claims and allocated claim adjustment expenses related to current year	127,610	90,640
Total paid	319,945	322,985
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	347,751	305,531	$ 372,488
Specialty Programs Business Unit [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total incurred	19,624
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Total paid	15,390
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	4,234
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2011 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		196	196	$ 196	$ 196	$ 196	$ 196	$ 196	$ 317
Incurred claims and claim adjustment expenses related to current year	196
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	196	196	196	196	196	196	196	196	$ 196
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2012 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		2,045	2,045	2,045	3,885	2,045	2,045	3,001
Incurred claims and claim adjustment expenses related to current year	$ 2,045
Cumulative number of reported claims | claim	3
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 2,045	2,045	2,045	2,045	2,045	2,045	2,045	$ 2,045
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2013 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		2,302	2,302	2,076	1,561	2,543	1,595
Incurred claims and claim adjustment expenses related to current year	$ 2,302
Cumulative number of reported claims | claim	2
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 2,302	2,302	2,302	2,076	1,561	1,561	$ 1,489
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2014 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		1,575	1,575	2,039	666	1,623
Incurred claims and claim adjustment expenses related to current year	$ 1,575
Cumulative number of reported claims | claim	5
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 1,575	1,575	1,575	1,575	1,502	$ 758
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized in 2015 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		752	752	1,629	1,683
Incurred claims and claim adjustment expenses related to current year	$ 752
Cumulative number of reported claims | claim	2
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 752	752	752	1,629	$ 1,515
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized in 2016 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		1,178	1,200	478
Incurred claims and claim adjustment expenses related to current year	$ 1,178
Cumulative number of reported claims | claim	1
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 1,178	1,178	1,139	$ 1,139
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized in 2017 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		1,775	955
Incurred claims and claim adjustment expenses related to current year	1,801
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 55
Cumulative number of reported claims | claim	23
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 1,551	1,556	$ 36
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2018 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable net prior year development		3,598
Incurred claims and claim adjustment expenses related to current year	4,368
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 440
Cumulative number of reported claims | claim	88
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 1,290	$ 911
Specialty Programs Business Unit [Member] | Loss Adjustment Expenses Recognized In 2019 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Incurred claims and claim adjustment expenses related to current year	5,407
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,481
Cumulative number of reported claims | claim	56
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to current year	$ 4,501