Segment Information Underwriting Margins and Combined Ratios for our Underwriting Operations (Detail) (Underwriting Operations)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Underwriting Margin	7.40%	6.70%	7.00%	7.10%
Combined Ratio	92.60%	93.30%	93.00%	92.90%
Personal Lines
Segment Reporting Information [Line Items]
Underwriting Margin	6.40%	6.70%	6.30%	7.40%
Combined Ratio	93.60%	93.30%	93.70%	92.60%
Personal Lines | Agency Channel
Segment Reporting Information [Line Items]
Underwriting Margin	6.40%	6.10%	7.20%	7.20%
Combined Ratio	93.60%	93.90%	92.80%	92.80%
Personal Lines | Direct Channel
Segment Reporting Information [Line Items]
Underwriting Margin	6.30%	7.50%	5.20%	7.60%
Combined Ratio	93.70%	92.50%	94.80%	92.40%
Commercial Lines
Segment Reporting Information [Line Items]
Underwriting Margin	17.50%	7.30%	13.50%	5.40%
Combined Ratio	82.50%	92.70%	86.50%	94.60%