Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Jul. 25, 2016
Subsequent Event [Line Items]
Cash dividends declared per common share (in dollars per share)		$ 0.18	$ 0.16	$ 0.34	$ 0.32	$ 0.3
Estimated total cash dividend				$ 16,438	$ 15,404	$ 14,820
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common share (in dollars per share)	$ 0.18
Estimated total cash dividend	$ 8,700
Dividends payable, date to be paid	Oct. 27, 2016
Dividends payable, date of record	Oct. 06, 2016
Revolving Credit Facility
Subsequent Event [Line Items]
Credit facility, total available credit		$ 300,000		$ 300,000
Revolving Credit Facility | Subsequent Event
Subsequent Event [Line Items]
Credit facility, total available credit							$ 300,000