Derivative and Other Fair Value Instruments - Additional Information (Details)	1 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2017 USD ($) DerivativeInstrument	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)		$ 94,700,000	$ 113,900,000
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net		21,400,000
Proceeds from settlement of derivative instruments		$ 1,296,000
Forward Starting Swaps [Member]
Derivative [Line Items]
Proceeds from settlement of derivative instruments	$ 1,300,000
Forward Starting Swaps settled | DerivativeInstrument	4
Public Notes, Face Value	$ 400,000,000
Debt instrument, term	10 years