Subsequent Event Subsequent Event	6 Months Ended
Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	Note 17. Subsequent Event In July 2017, White Mountains repurchased 235,000 common shares for $199.8 million.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

No definition available.

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