Real Estate and Lending Activities - Development Activities - Additional Information (Detail) € in Millions	Sep. 09, 2015 EUR (€)	Sep. 30, 2016 Facility
2015 [Member] | AXA Real Estate [Member]
Business Acquisition [Line Items]
Ownership interest in joint venture under the equity method	50.00%
Acute Care Facilities in Altoona [Member] | Development Activities [Member]
Business Acquisition [Line Items]
Number of facilities constructed | Facility		13
Acute Care Hospital [Member] | 2015 [Member] | Spain [Member] | AXA Real Estate [Member]
Business Acquisition [Line Items]
Estimated total development cost | €	€ 21.4