Dividends (Narrative) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended		0 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Oct. 08, 2013 Subsequent Event [Member]
Subsequent Event [Line Items]
Total cash dividends paid	$ 11,829	$ 11,516	$ 11,415	$ 34,760	$ 32,866
Dividend declared date						Oct. 08, 2013
Dividend per common share to be paid						$ 0.17
Dividend payable date	Sep. 20, 2013	Jun. 14, 2013	Mar. 15, 2013			Dec. 20, 2013
Dividend record date	Aug. 16, 2013	May 10, 2013	Feb. 22, 2013			Nov. 15, 2013