XML 179 R126.htm IDEA: XBRL DOCUMENT

Employee Share-Based Incentive Compensation Plans (OneBeacon - Restricted Stock Units) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended					1 Months Ended	12 Months Ended
	Dec. 31, 2012 One Beacon Restricted Stock	Dec. 31, 2011 One Beacon Restricted Stock	Dec. 31, 2012 One Beacon Long Term Incentive Plan	Dec. 31, 2011 One Beacon Long Term Incentive Plan	Dec. 31, 2010 One Beacon Long Term Incentive Plan	Mar. 31, 2008 One Beacon Long Term Incentive Plan One Beacon Restricted Stock	Dec. 31, 2011 One Beacon Long Term Incentive Plan Restricted Stock Units (RSUs)	Dec. 31, 2010 One Beacon Long Term Incentive Plan Restricted Stock Units (RSUs)
Share-based compensation arrangement by share-based payment award
New grants (in shares)			181,290	194,900	270,691	116,270
Percentage of growth in book value per share						4.00%
Expense recognized	$ 2.6	$ 0.9	$ 0.8	$ (2.2)	$ (10.2)		$ 0.1	$ 0.5

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References+ Details