Reserves for Unpaid Losses and Loss Adjustment Expenses (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	$ 500	$ 1,700
Prior Year Claims and Claims Adjustment Expense	(489)	(1,717)
Loss and Loss Adjustment Expenses Incurred in 2016 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	1,000
Loss and Loss Adjustment Expenses Incurred in 2015 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		3,600
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	600
Loss and Loss Adjustment Expenses Incurred in 2014 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		200
Loss and Loss Adjustment Expenses Incurred in 2014 and Prior Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	100
Loss And Loss Adjustment Expenses Incurred In 2013 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		1,700
Loss and Loss Adjustment Expenses Incurred In 2012 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		1,100
Loss and Loss Adjustment Expenses Incurred in 2011 and Prior Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		700
Standard Commercial P & C Business Unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	1,500	200
Occupational Accident [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		600
Occupational Accident [Member] | Loss and Loss Adjustment Expenses Incurred in 2015 and Prior Accident Years [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	700
Commercial Property and General Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	2,200	800
Workers Compensation Business Unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		200
Specailty Commercial Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	300	100
MGA Commerical Products [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		2,200
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	600
Commerical Excess Liability [Member] | Loss and Loss Adjustment Expenses Incurred in 2016 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	100
Medical Professional Liability Products [Member] | Loss and Loss Adjustment Expenses Incurred in 2016 Accident Year [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	200
Personal Lines Business Unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense		$ 1,000
Specialty Personal Lines [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Unfavorable Adjustment to Prior Years Liability for Unpaid Claims and Claims Adjustment Expense	$ 700