Common Stock (Details) - $ / shares					3 Months Ended								12 Months Ended
	Jan. 27, 2017	Jan. 03, 2017	Sep. 25, 2014	Sep. 24, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Dividends declared (in dollars per share)					$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.08	$ 0.08	$ 0.08	$ 0.08
Dividends paid (in dollars per share)													$ 0.36	$ 0.32	$ 0.28
Subsequent Event
Class of Stock [Line Items]
Dividends declared (in dollars per share)		$ 0.10
Dividends paid (in dollars per share)	$ 0.10
Share Repurchase Agreement with Capital Southwest Corporation and Capital Southwest Venture Corporation
Class of Stock [Line Items]
Authorized shares to be repurchased (in shares)				849,690
Purchase price per share (in dollars per share)				$ 40.255
Share Price (in dollars per share)				$ 41.50
Retirement of shares (in shares)			849,690