Dividends (Narrative) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		0 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Jul. 09, 2013 Subsequent Event [Member]
Subsequent Event [Line Items]
Total cash dividends paid	$ 11,516	$ 11,415	$ 22,931	$ 21,803
Dividend declared date					Jul. 09, 2013
Dividend per common share to be paid					$ 0.16875
Dividend payable date	Jun. 14, 2013	Mar. 15, 2013			Sep. 20, 2013
Dividend record date	May 10, 2013	Feb. 22, 2013			Aug. 16, 2013