Subsequent Events (Details) $ / shares in Units, shares in Thousands, bed in Thousands, $ in Millions				12 Months Ended
	Feb. 22, 2017 USD ($) bed	Feb. 16, 2017 shares	Feb. 06, 2017 $ / shares	Dec. 31, 2016 $ / shares shares	Dec. 31, 2015 $ / shares	Dec. 31, 2014 $ / shares
Subsequent Event [Line Items]
Dividends declared per share (in dollars per share) | $ / shares				$ 2.60	$ 2.51	$ 2.33
Restricted Stock Award
Subsequent Event [Line Items]
Granted shares (in shares)				349
Subsequent Event
Subsequent Event [Line Items]
Options, grants in period (in shares)		310
Dividends declared per share (in dollars per share) | $ / shares			$ 0.70
Subsequent Event | Restricted Stock Award
Subsequent Event [Line Items]
Granted shares (in shares)		418
Subsequent Event | Performance-based Restricted Stock
Subsequent Event [Line Items]
Granted shares (in shares)		115
Performance period		3 years
Community Education Centers | Subsequent Event
Subsequent Event [Line Items]
Cash consideration | $	$ 360
Facility, number of beds | bed	12