Brookdale Lease Amendments and Terminations and the Formation of Two RIDEA Joint Ventures ("Brookdale Transaction") - Fair Value Measurement Techniques and Quantitative Information (Details) $ in Thousands	Aug. 29, 2014 USD ($)
NNN-leased Portfolio
Fair Value Inputs [Abstract]
Exercise probability (as a percent)	100.00%
NNN-leased Portfolio | Minimum
Fair Value Inputs [Abstract]
Capitalization Rates	7.50%
Discount Rate	10.50%
NNN-leased Portfolio | Maximum
Fair Value Inputs [Abstract]
Capitalization Rates	9.25%
Discount Rate	11.00%
NNN-leased Portfolio | Income approach
Fair Value Inputs Quantitative Information
Fair value of forfeited purchase options	$ (129,000)
RIDEA JV
Fair Value Inputs [Abstract]
Exercise probability (as a percent)	100.00%
RIDEA JV | Income approach
Fair Value Inputs Quantitative Information
Fair value of forfeited purchase options	$ (23,000)
Brookdale Senior Living | NNN-leased Portfolio
Fair Value Inputs [Abstract]
Range of rent coverage ratio	1.20
Rent Growth Rate	3.00%
Brookdale Senior Living | NNN-leased Portfolio | Minimum
Fair Value Inputs [Abstract]
Discount Rate	8.00%
Brookdale Senior Living | NNN-leased Portfolio | Maximum
Fair Value Inputs [Abstract]
Discount Rate	8.50%
Brookdale Senior Living | NNN-leased Portfolio | Income approach
Fair Value Inputs Quantitative Information
Fair value of rental payment concessions	$ 76,000
Brookdale Senior Living | RIDEA JV
Fair Value Inputs [Abstract]
Range of rent coverage ratio	1.20
Rent Growth Rate	3.00%
EBITDAR Growth Rate (as a percent)	5.50%
Brookdale Senior Living | RIDEA JV | Minimum
Fair Value Inputs [Abstract]
Discount Rate	8.00%
Brookdale Senior Living | RIDEA JV | Maximum
Fair Value Inputs [Abstract]
Discount Rate	11.00%
Brookdale Senior Living | RIDEA JV | Income approach
Fair Value Inputs Quantitative Information
Fair value of forfeited rental payments revenue	$ 131,000