Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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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.

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The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

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- Definition

Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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The cash outflow for a financial contract that meets the hedge criteria as either cash flow hedge, fair value hedge or hedge of net investment in foreign operations.

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Financial Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative [Line Items]
Premium payments on interest rate cap agreements				$ 12.6	$ 0.0
Interest gain (loss) reclassified to earnings (less than)					1.0
Cap agreement effective 12/31/18-12/31/20
Derivative [Line Items]
Notional amount	$ 1,400.0	$ 1,400.0		1,400.0
Premium payments on interest rate cap agreements		$ 13.0
Interest Rate Contract
Derivative [Line Items]
Unrealized gain (loss) on effective portion of interest rate cap agreements	2.0		$ (1.0)	5.0	$ (2.0)
Amount expected to be reclassified from AOCL to interest expense				(5.0)
Derivative
Derivative [Line Items]
Interest gain (loss) reclassified to earnings (less than)	$ (1.0)			$ (2.0)