Significant Transactions (Tables)

12 Months Ended

Dec. 31, 2017

Significant Transactions [Abstract]

Reconciliation to the increase in book value

The following table presents a reconciliation of the gain reported in discontinued operations to the impact to White Mountains’s book value:

Millions	Year ended December 31, 2016
Gain from sale of Tranzact reported in discontinued operations	$	51.9
Add back reclassification from continuing operations for the    release of a tax valuation allowance	30.2
Increase to White Mountains’s book value from sale of Tranzact	$	82.1