Debt - Narrative (Details)		3 Months Ended
	Oct. 22, 2015 USD ($) entity	Mar. 31, 2018 USD ($)	Mar. 31, 2017	Dec. 31, 2017 USD ($)	Nov. 22, 2016 USD ($)	Apr. 01, 2016 USD ($)	Aug. 11, 2015 USD ($)	Dec. 12, 2014 USD ($)
Debt Instrument [Line Items]
Term to determine contractual rate			360 days
Weighted average interest rate (percent)		3.23%
Term to determine weighted average rate		365 days
Number of wholly owned SPE | entity	6
Long-term debt		$ 482,122,000		$ 481,848,000
Key Bank Credit Facility | Line of Credit
Debt Instrument [Line Items]
Contractual interest rate		3.17%
Weighted average interest rate (percent)		3.21%
Term of loan		4 years
Revolving credit facility, extension term		1 year
AIG Loan | Notes Payable, Other Payables
Debt Instrument [Line Items]
Contractual interest rate	4.15%	4.15%
Term of loan	10 years
Duration monthly payments of interest only	5 years	5 years
Long-term debt	$ 127,000,000
Revolving Credit Facility | Key Bank Credit Facility
Debt Instrument [Line Items]
Remaining borrowing capacity		$ 143,900,000
Revolving credit facility current borrowing capacity					$ 550,000,000		$ 410,000,000	$ 250,000,000.0
Revolving credit facility, maximum borrowing capacity								$ 1,250,000,000.00
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis rate (percent)		1.67%
London Interbank Offered Rate (LIBOR) | Key Bank Credit Facility | Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate (percent)		1.50%
Interest Rate Swap
Debt Instrument [Line Items]
Notional amount		$ 200,000,000.0				$ 100,000,000.0