Acquisitions (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended			0 Months Ended		0 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 27, 2014 Selective Insurance Company of America Self-Insured Pooled Group [Member]	Apr. 01, 2014 Summit Holdings Southeast, Inc [Member]	Apr. 01, 2014 Subsequent Event [Member] Summit Holdings Southeast, Inc [Member]	Dec. 31, 2013 Minimum [Member] Summit Holdings Southeast, Inc [Member]
Business Acquisition [Line Items]
Payments to acquire business	$ 8	$ 0		$ 8		$ 260
In-force gross written premiums of acquired book of business				38
Capital contributions in acquired business						140
Total capital investment in acquired business						400
Total assets of acquired business	42,770		42,087		1,500
Net written premiums of acquired business							$ 500