Subsequent Events (Details)				3 Months Ended		6 Months Ended
	Jul. 31, 2015 $ / shares	Jun. 30, 2015 bed	Jun. 01, 2015 bed	Jun. 30, 2015 bed $ / shares	Jun. 30, 2014 $ / shares	Jun. 30, 2015 bed $ / shares	Jun. 30, 2014 $ / shares	Jul. 06, 2015 facility bed	Jul. 01, 2015 bed
Subsequent Event [Line Items]
Dividends declared per share | $ / shares				$ 0.62	$ 0.57	$ 1.24	$ 1.14
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share | $ / shares	$ 0.62
Oklahoma, Michigan and California | Activation Of Facilities Contract | Subsequent Event
Subsequent Event [Line Items]
Number of company owned facilities | facility								3
Number of beds in a facility								4,320
Great Plains Correctional Facility | Intake Of Offenders
Subsequent Event [Line Items]
Contract term, operation of facility			10 years
Great Plains Correctional Facility | OKLAHOMA | Intake Of Offenders
Subsequent Event [Line Items]
Number of beds in a facility			1,940
North Lake Correctional Facility | Intake Of Offenders
Subsequent Event [Line Items]
Number of beds in a facility		1,740		1,740		1,740
Contract term, operation of facility		5 years
Adelanto Detention Facility | Subsequent Event
Subsequent Event [Line Items]
Number of beds in a facility									640