Subsequent Events Subsequent Events (Details)					6 Months Ended
	Jul. 28, 2016 USD ($) extension	Jul. 11, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 29, 2016	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Subsequent Event [Line Items]
Repayments of long-term debt					$ 160,597,000	$ 314,377,000
Long-term debt			$ 1,740,487,000		1,740,487,000		$ 1,724,449,000
Subsequent Event
Subsequent Event [Line Items]
Leverage ratio	7.00%
Term Loan
Subsequent Event [Line Items]
Long-term debt			400,000,000		400,000,000
Term Loan | Subsequent Event
Subsequent Event [Line Items]
Long-term debt	$ 400,000,000
Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity			500,000,000		500,000,000
Long-term debt			(1,398,000)		(1,398,000)		$ 18,273,000
Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Maximum borrowing capacity	500,000,000
7-year unsecured term loan | Term Loan
Subsequent Event [Line Items]
Long-term debt			$ 200,000,000		$ 200,000,000
Term			7 years	7 years
7-year unsecured term loan | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Long-term debt	$ 200,000,000
Term	7 years
Amended Credit Agreement - Term Loan A | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Long-term debt	$ 200,000,000
Number of extensions | extension	1
Extension	6 months
Amended Credit Agreement - Term Loan B | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Long-term debt	$ 200,000,000
Option to increase borrowings	$ 200,000,000
Amended Credit Agreement | Subsequent Event
Subsequent Event [Line Items]
Leverage ratio	6.75%
Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 1,000,000,000
Number of extensions | extension	2
Extension	6 months
Minimum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Unused commitment fee	12.50%
Minimum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Facility fee	15.00%
Unused commitment fee	12.50%
Maximum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Unused commitment fee	25.00%
Maximum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Facility fee	25.00%
Unused commitment fee	30.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Minimum | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	135.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Minimum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	140.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Minimum | Amended Credit Agreement - Term Loan A | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	135.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Minimum | Amended Credit Agreement - Term Loan B | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	130.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Minimum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	135.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Maximum | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	190.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Maximum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	200.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Maximum | Amended Credit Agreement - Term Loan A | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	190.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Maximum | Amended Credit Agreement - Term Loan B | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	190.00%
London Interbank Offered Rate (LIBOR) Using Credit Rating As Basis | Maximum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	195.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Minimum | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	95.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Minimum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	87.50%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Minimum | Amended Credit Agreement - Term Loan A | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	95.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Minimum | Amended Credit Agreement - Term Loan B | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	90.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Minimum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	85.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Maximum | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	190.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Maximum | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	170.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Maximum | Amended Credit Agreement - Term Loan A | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	190.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Maximum | Amended Credit Agreement - Term Loan B | Term Loan | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	175.00%
London Interbank Offered Rate (LIBOR) Using Investment Grade Credit Rating As Basis | Maximum | Amended Credit Agreement | Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Basis spread on variable rate	155.00%
Pine Ridge Crossing | Subsequent Event
Subsequent Event [Line Items]
Repayments of long-term debt		$ 16,500,000
Riverchase Plaza | Subsequent Event
Subsequent Event [Line Items]
Repayments of long-term debt		$ 9,900,000