Dividends - Narrative (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended		0 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Oct. 14, 2014 Subsequent Event [Member]
Subsequent Event [Line Items]
Aggregate cash dividends paid	$ 12,335	$ 12,186	$ 12,077	$ 36,598	$ 34,760
Dividend declared date						Oct. 14, 2014
Dividend declared per common share (in dollars per share)						$ 0.175
Dividend payable date	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014			Dec. 26, 2014
Dividend record date	Aug. 22, 2014	May 23, 2014	Feb. 21, 2014			Nov. 21, 2014