Summary of Significant Accounting Policies - Additional Information (Detail)
$ in Millions |
3 Months Ended |
9 Months Ended |
12 Months Ended |
|
|
Sep. 30, 2016
USD ($)
Community
shares
|
Mar. 31, 2016
USD ($)
|
Sep. 30, 2015
USD ($)
Community
shares
|
Sep. 30, 2016
USD ($)
Community
shares
|
Sep. 30, 2015
USD ($)
shares
|
Dec. 31, 2009
shares
|
Dec. 31, 2015
USD ($)
|
| Accounting Policies [Line Items] |
|
|
|
|
|
|
|
| Senior housing communities on lease by company | Community |
50
|
|
|
50
|
|
|
|
| Communities on operating lease | Community |
48
|
|
|
48
|
|
|
|
| Senior housing communities on capital lease and financing obligations | Community |
2
|
|
|
2
|
|
|
|
| Resident receivables due period |
|
|
|
30 days
|
|
|
|
| Allowance for doubtful accounts | $ |
$ 3.9
|
|
|
$ 3.9
|
|
|
$ 3.2
|
| Adjustments to valuation allowance | $ |
3.0
|
|
$ 1.3
|
6.4
|
$ 3.1
|
|
|
| Deferred tax assets valuation allowance | $ |
$ 28.7
|
|
$ 20.3
|
$ 28.7
|
$ 20.3
|
|
|
| Uncertain tax position maximum percentage |
|
|
|
50.00%
|
|
|
|
| Outstanding unvested restricted stock | shares |
1,028,000
|
|
778,000
|
1,038,000
|
787,000
|
|
|
| Repurchase of common stock | shares |
|
|
|
144,315
|
|
349,800
|
|
| Property and Equipment [Member] |
|
|
|
|
|
|
|
| Accounting Policies [Line Items] |
|
|
|
|
|
|
|
| Valuation adjustments | $ |
|
$ 1.3
|
|
$ 1.7
|
|
|
|
| Texas [Member] |
|
|
|
|
|
|
|
| Accounting Policies [Line Items] |
|
|
|
|
|
|
|
| Number of communities consolidated | Community |
38
|
|
37
|
|
|
|
|