Fair Value of Financial Instruments (Details)	3 Months Ended					9 Months Ended
	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015	Mar. 31, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Mar. 02, 2015 USD ($)	Dec. 31, 2014
Fair Value of Financial Instruments (Details) [Line Items]
Long-term Debt	$ 1,349,175,000					$ 1,349,175,000		$ 1,000,000,000
Long-term Debt, Fair Value	1,400,000,000					$ 1,400,000,000		1,000,000,000
Derivative, Description of Terms						Company pays a fixed rate of interest and receives a floating rate of interest equal to the one month LIBOR
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	4,261,000		$ (5,978,000)			$ (7,934,000)	$ (6,437,000)
Amount of losses reclassified from accumulated other comprehensive loss into interest expense	900,000		800,000			2,900,000	1,000,000
Net unrealized losses in accumulated other comprehensive loss expected to be reclassified into interest expense within the next 12 months	3,900,000					3,900,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(9,991,000)					(9,991,000)		$ (2,057,000)
Repayments of Unsecured Debt						0	100,000,000
Repayment of $100 Million Unsecured Term Loan and Termination of Interest Rate Swap May 2015 [Member] | From Inception through March 2, 2015 Designated as a Cash Flow Hedge and from March 3, 2015 through Termination Date No Longer Designated as a Cash Flow Hedge [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Interest Rate Swap Termination, Cash Settlement							1,100,000
Derivative, Notional Amount			100,000,000				100,000,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax					$ (300,000)
Amount of losses reclassified from accumulated other comprehensive loss into net income							800,000
Accumulated Other Comprehensive Income (Loss), Net of Tax									$ (800,000)
Repayments of Unsecured Debt							100,000,000
Realized Gain (Loss) on Derivative							(1,100,000)
Not Designated as Hedging Instrument [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Interest Rate Swap Termination, Cash Settlement		$ 100,000
Number of Interest Rate Derivatives Held										4
Number of Interest Rate Derivatives Matured or Terminated		1		1	2
Designated as Hedging Instrument [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	0		$ 0			$ 0	$ 0
Designated as Hedging Instrument [Member] | $212.5 Million Term Loan Interest Rate Swap [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Derivative Inception Date						May 2015
Derivative, Notional Amount	212,500,000					$ 212,500,000
Designated as Hedging Instrument [Member] | $110.0 Million Term Loan Interest Rate Swap [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Derivative Inception Date						July 2015
Derivative, Notional Amount	110,000,000					$ 110,000,000
Designated as Hedging Instrument [Member] | $50.0 Million Term Loan Interest Rate Swap [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Derivative Inception Date						April 2016
Derivative, Notional Amount	50,000,000					$ 50,000,000
Designated as Hedging Instrument [Member] | $100.0 Million Term Loan Interest Rate Swap [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Derivative Inception Date						April 2016
Derivative, Notional Amount	100,000,000					$ 100,000,000
Designated as Hedging Instrument [Member] | Conversion of Loan to Fixed Rate Mortgage and Assignment of Swap to Lender at no Cost [Member] | $24.0 Million Mortgage Loan Interest Rate Swap [Member]
Fair Value of Financial Instruments (Details) [Line Items]
Derivative Inception Date						May 2016
Derivative, Notional Amount	$ 24,000,000					$ 24,000,000
Debt Conversion, Date						Aug. 10, 2016
Debt Instrument, Interest Rate, Stated Percentage	4.37%					4.37%
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ 1,000,000	$ (1,000,000)