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- Definition

Fair value inputs offered quotes per fixed income investment.

+ References

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+ References

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
-Paragraph 2
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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

The fair value of notes issued in noncash investing and financing activities.

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-Name Accounting Standards Codification
-Topic 230
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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Fair Value Measurements - Narrative (Details) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
Fair Value Measurements - Narrative (Details) $ in Millions	Sep. 30, 2017 USD ($) quote / Investment	Dec. 31, 2016 USD ($) quote / Investment	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2017 USD ($) quote / Investment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) quote / Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Quotes per fixed income investment \| quote / Investment	2.0	2.1				2.0		2.1
Quotes per equity investment \| quote / Investment	4.0	3.9				4.0		3.9
Silverton 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued					$ 85.0
Silverton 2015, Third-party Funded
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued					$ 70.0
Silverton 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued				$ 125.0
Silverton 2016, Third-party Funded
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued				$ 100.0
Silverton 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued		$ 130.0
Silverton 2017, Third-party Funded
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Issued		105.0
Non-U.S. government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 1 to Level 2 transfers, amount		$ 83.9						$ 83.9
Fair Value, Measurements, Recurring \| Level 3 \| Silverton
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repayments of debt								$ 89.3
Fair Value, Measurements, Recurring \| Level 3 \| Silverton 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Level 3 liabilities settled			$ 0.3				$ 89.3
Fair Value, Measurements, Recurring \| Level 3 \| Silverton 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Level 3 liabilities settled	$ 1.4					$ 115.9