Significant New Business	12 Months Ended
Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant New Business	SIGNIFICANT NEW BUSINESS 2016 On February 17, 2016, we entered into a reinsurance agreement with Allianz SE ("Allianz") to reinsure portfolios of Allianz's run-off business. Pursuant to the reinsurance agreement, our subsidiary will reinsure 50% of certain portfolios of workers' compensation, construction defect, and asbestos, pollution, and toxic tort business originally held by Fireman's Fund Insurance Company, and in the process will assume net reinsurance reserves of approximately $1.1 billion. Affiliates of Allianz will retain approximately $1.1 billion of reinsurance premium as funds withheld collateral for the obligations of our subsidiary under the reinsurance agreement and we will transfer approximately $110.0 million to a reinsurance trust to further support our subsidiary's obligations. We have also provided a limited parental guarantee, which is subject to a maximum cap. The combined monetary total of the support offered by us through the trust and parental guarantee will initially be capped at $270.0 million. Consummation of the transaction is subject to final regulatory approval. In addition to the reinsurance transaction described above, we have entered into a consulting agreement with San Francisco Reinsurance Company, an affiliate of Allianz, with respect to the entire $2.2 billion portfolio, including the 50% share retained by affiliates of Allianz. 2015 Doctors On November 30, 2015, we completed the assignment and assumption of a portfolio of primarily workers' compensation business from The Doctors Company and its affiliates. Total assets and liabilities assumed were approximately $29.5 million. Sun Life On September 30, 2015, we entered into two 100% reinsurance agreements and a related administration services agreement with Sun Life pursuant to which we reinsured all of the run-off workers' compensation carve-out and occupational accident business of Sun Life. We assumed reinsurance reserves of $128.3 million, received total assets of $122.5 million and recorded a deferred charge of $5.8 million, included in other assets. We transferred approximately $30.6 million of additional funds into trust to further support our obligations under the reinsurance agreements. We provided limited parental guarantees, subject to an overall maximum of approximately $36.8 million. Voya Financial On May 27, 2015, we entered into two 100% reinsurance agreements and related administration services agreements with a subsidiary of Voya, pursuant to which we reinsured all of the run-off workers' compensation and occupational accident assumed reinsurance business of the Voya subsidiary and that of its Canadian branch. Pursuant to the transaction, the Voya subsidiary transferred assets into two reinsurance collateral trusts securing our obligations under the reinsurance agreements. We assumed reinsurance reserves of $572.4 million, received total assets of $307.0 million and recorded a deferred charge of $265.4 million, included in other assets. We transferred approximately $67.2 million of additional funds to the trusts to further support our obligations under the reinsurance agreements. We provided a limited parental guarantee, subject to a maximum cap with respect to the reinsurance liabilities. As of December 31, 2015, the amount of the parental guarantee was $58.0 million. Reciprocal of America On January 15, 2015, we completed a loss portfolio transfer reinsurance transaction with Reciprocal of America (in Receivership) and its Deputy Receiver relating to a portfolio of workers' compensation business that has been in run-off since 2003. The total insurance reserves assumed were $162.1 million with an equivalent amount of cash and investments received as consideration. 2014 Shelbourne RITC Transactions On January 1, 2014, we entered into a reinsurance-to-close contract ("RITC") of the 2011 and prior underwriting years of account of a Lloyd’s syndicate, under which we assumed total net insurance reserves of approximately £17.0 million (approximately $28.1 million) for cash consideration of an equal amount. 2013 Shelbourne RITC Transactions On January 1, 2013, we entered into an RITC of the 2009 underwriting year of account of a Lloyd’s syndicate and a 100% quota share reinsurance agreement with another Lloyd’s syndicate in respect of its 2010 underwriting year of account, under which we assumed total gross insurance reserves of approximately £33.8 million (approximately $51.4 million) for cash consideration of an equal amount. American Physicians On April 26, 2013, we completed the assignment and assumption of a portfolio of workers’ compensation business from American Physicians Assurance Corporation and APSpecialty Insurance Company (collectively "APS"). Total assets and liabilities assumed were approximately $35.3 million.

SIGNIFICANT NEW BUSINESS

2016

On February 17, 2016, we entered into a reinsurance agreement with Allianz SE ("Allianz") to reinsure portfolios of Allianz's run-off business. Pursuant to the reinsurance agreement, our subsidiary will reinsure 50% of certain portfolios of workers' compensation, construction defect, and asbestos, pollution, and toxic tort business originally held by Fireman's Fund Insurance Company, and in the process will assume net reinsurance reserves of approximately $1.1 billion. Affiliates of Allianz will retain approximately $1.1 billion of reinsurance premium as funds withheld collateral for the obligations of our subsidiary under the reinsurance agreement and we will transfer approximately $110.0 million to a reinsurance trust to further support our subsidiary's obligations. We have also provided a limited parental guarantee, which is subject to a maximum cap. The combined monetary total of the support offered by us through the trust and parental guarantee will initially be capped at $270.0 million. Consummation of the transaction is subject to final regulatory approval.

In addition to the reinsurance transaction described above, we have entered into a consulting agreement with San Francisco Reinsurance Company, an affiliate of Allianz, with respect to the entire $2.2 billion portfolio, including the 50% share retained by affiliates of Allianz.

2015

Doctors

On November 30, 2015, we completed the assignment and assumption of a portfolio of primarily workers' compensation business from The Doctors Company and its affiliates. Total assets and liabilities assumed were approximately $29.5 million.

Sun Life

On September 30, 2015, we entered into two 100% reinsurance agreements and a related administration services agreement with Sun Life pursuant to which we reinsured all of the run-off workers' compensation carve-out and occupational accident business of Sun Life. We assumed reinsurance reserves of $128.3 million, received total assets of $122.5 million and recorded a deferred charge of $5.8 million, included in other assets. We transferred approximately $30.6 million of additional funds into trust to further support our obligations under the reinsurance agreements. We provided limited parental guarantees, subject to an overall maximum of approximately $36.8 million.

Voya Financial

On May 27, 2015, we entered into two 100% reinsurance agreements and related administration services agreements with a subsidiary of Voya, pursuant to which we reinsured all of the run-off workers' compensation and occupational accident assumed reinsurance business of the Voya subsidiary and that of its Canadian branch. Pursuant to the transaction, the Voya subsidiary transferred assets into two reinsurance collateral trusts securing our obligations under the reinsurance agreements. We assumed reinsurance reserves of $572.4 million, received total assets of $307.0 million and recorded a deferred charge of $265.4 million, included in other assets. We transferred approximately $67.2 million of additional funds to the trusts to further support our obligations under the reinsurance agreements. We provided a limited parental guarantee, subject to a maximum cap with respect to the reinsurance liabilities. As of December 31, 2015, the amount of the parental guarantee was $58.0 million.

Reciprocal of America

On January 15, 2015, we completed a loss portfolio transfer reinsurance transaction with Reciprocal of America (in Receivership) and its Deputy Receiver relating to a portfolio of workers' compensation business that has been in run-off since 2003. The total insurance reserves assumed were $162.1 million with an equivalent amount of cash and investments received as consideration.

2014

Shelbourne RITC Transactions

On January 1, 2014, we entered into a reinsurance-to-close contract ("RITC") of the 2011 and prior underwriting years of account of a Lloyd’s syndicate, under which we assumed total net insurance reserves of approximately £17.0 million (approximately $28.1 million) for cash consideration of an equal amount.

2013

Shelbourne RITC Transactions

On January 1, 2013, we entered into an RITC of the 2009 underwriting year of account of a Lloyd’s syndicate and a 100% quota share reinsurance agreement with another Lloyd’s syndicate in respect of its 2010 underwriting year of account, under which we assumed total gross insurance reserves of approximately £33.8 million (approximately $51.4 million) for cash consideration of an equal amount.

American Physicians

On April 26, 2013, we completed the assignment and assumption of a portfolio of workers’ compensation business from American Physicians Assurance Corporation and APSpecialty Insurance Company (collectively "APS"). Total assets and liabilities assumed were approximately $35.3 million.