Fair value inputs offered quotes per fixed income investment.

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

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.

+ References

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-Publisher FASB
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- Definition

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

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- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

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-Publisher FASB
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Fair Value Measurements - Narrative (Details) $ in Millions	3 Months Ended					12 Months Ended
Fair Value Measurements - Narrative (Details) $ in Millions	Mar. 31, 2019 USD ($) quote / Investment	Mar. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2018 USD ($) quote / Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Quotes per fixed income investment \| quote / Investment	2.2					2.0
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
Fair Value, Measurements, Recurring \| Level 3 \| Silverton
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repayments of debt						$ 115.6
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		$ 45.8
Fair Value, Measurements, Recurring \| Level 3 \| Silverton 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of Level 3 liabilities settled	$ 0.2