Equity and Dividends (Schedule of Quarterly Dividends Declared and Paid) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
First Quarter 2016 [Member]
Dividends Payable [Line Items]
Declaration date	May 09, 2016
Dividends per share	$ 0.1600
Record date	May 24, 2016
Total dividends	$ 17,022
Payment date	Jun. 14, 2016
Second Quarter 2016 [Member]
Dividends Payable [Line Items]
Declaration date	Aug. 05, 2016
Dividends per share	$ 0.1700
Record date	Sep. 02, 2016
Total dividends	$ 18,127
Payment date	Sep. 23, 2016
First Quarter 2015 [Member]
Dividends Payable [Line Items]
Declaration date		May 07, 2015
Dividends per share		$ 0.1400
Record date		May 29, 2015
Total dividends		$ 14,955
Payment date		Jun. 19, 2015
Second Quarter 2015 [Member]
Dividends Payable [Line Items]
Declaration date		Aug. 06, 2015
Dividends per share		$ 0.1600
Record date		Sep. 04, 2015
Total dividends		$ 17,147
Payment date		Sep. 25, 2015
Fourth Quarter 2015 [Member]
Dividends Payable [Line Items]
Declaration date	Jan. 15, 2016
Dividends per share	$ 0.1600
Record date	Feb. 12, 2016
Total dividends	$ 17,154
Payment date	Mar. 04, 2016
Fourth Quarter 2014 [Member]
Dividends Payable [Line Items]
Declaration date		Jan. 12, 2015
Dividends per share		$ 0.1400
Record date		Feb. 13, 2015
Total dividends		$ 15,089
Payment date		Mar. 06, 2015