Segment Information (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Revenue and Income (Loss) Before Income Taxes for Each Segment

Revenue and income (loss) before income taxes for each segment were as follows:

	For the Years Ended December 31,
(in millions)	2016		2015		2014
Revenue:
Earned premiums
Excess and Surplus Lines	$	485.3	$	471.2	$	444.6
Commercial Specialty		364.2		344.2		332.5
International Specialty		154.5		146.4		144.8
Syndicate 1200		406.4		409.7		414.6
Run-off Lines		0.4		0.4		1.6
Total earned premiums		1,410.8		1,371.9		1,338.1
Net investment income
Excess and Surplus Lines		45.2		32.3		43.2
Commercial Specialty		26.7		19.9		25.6
International Specialty		16.8		11.4		11.3
Syndicate 1200		11.9		8.9		10.9
Run-off Lines		11.3		8.1		12.0
Corporate and Other		3.2		8.0		3.1
Total net investment income		115.1		88.6		106.1
Fee and other income		24.5		22.2		20.7
Net realized investment and other gains		26.1		24.1		74.5
Total revenue	$	1,576.5	$	1,506.8	$	1,539.4

	For the Years Ended December 31,
(in millions)	2016			2015			2014
Income (loss) before income taxes
Excess and Surplus Lines	$	88.4		$	81.4		$	103.4
Commercial Specialty		86.0			43.0			24.8
International Specialty		38.2			29.0			23.8
Syndicate 1200		13.4			35.4			45.2
Run-off Lines		(15.2	)		(7.4	)		(20.7	)
Total segment income before taxes		210.8			181.4			176.5
Corporate and Other		(55.0	)		(28.0	)		(35.0	)
Net realized investment and other gains		26.1			24.1			74.5
Total income before income taxes	$	181.9		$	177.5		$	216.0

Schedule of Earned Premiums by Geographic Location

The table below presents earned premiums by geographic location. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated.

	For the Years Ended December 31,
(in millions)	2016		2015		2014
Bermuda	$	112.6	$	103.4	$	101.5
Brazil		39.2		43.1		44.3
Malta		2.1		1.9		2.1
United Kingdom		406.9		407.4		411.7
United States		850.0		816.1		778.5
Total earned premiums	$	1,410.8	$	1,371.9	$	1,338.1

Identifiable Assets

The following table represents identifiable assets:

	December 31,
(in millions)	2016		2015
Excess and Surplus Lines	$	2,259.3	$	2,174.8
Commercial Specialty		1,701.9		1,511.7
International Specialty		970.6		877.2
Syndicate 1200		1,386.3		1,216.5
Run-off Lines		537.0		558.4
Corporate and Other		349.9		287.0
Total	$	7,205.0	$	6,625.6

Schedule of Goodwill and Intangible Assets Net of Accumulated Amortization

The following table represents goodwill and intangible assets, net of accumulated amortization as of December 31:

	Goodwill				Intangible Assets, Net of Accumulated Amortization
(in millions)	2016		2015		2016		2015
Excess and Surplus Lines	$	68.4	$	68.4	$	—	$	—
Commercial Specialty		55.1		55.1		3.7		6.3
Syndicate 1200		28.7		28.7		64.0		67.0
Total	$	152.2	$	152.2	$	67.7	$	73.3