Shareholder's Equity (Schedule of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period, Number of Shares	158,721	270,464	1,662,830
Options exercised, Number of Shares	(113,220)	(111,743)	(1,392,366)
Options terminated, Number of Shares	(11,750)
Outstanding at end of period, Number of Shares	33,751	158,721	270,464	1,662,830
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period, Weighted Average Exercise Price (usd per share)	$ 22.89	$ 23.16	$ 23.82
Options exercised, Weighted Average Exercise Price (usd per share)	22.81	23.53	23.95
Options terminated, Weighted Average Exercise Price (usd per share)	23.42
Outstanding at end of period, Weighted Average Exercise Price (usd per share)	$ 22.98	$ 22.89	$ 23.16	$ 23.82
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding at beginning of period, Weighted Average Remaining Contractual Life (in years)	1 year 36 days	1 year 256 days	2 years 182 days	2 years 328 days
Outstanding at end of period, Weighted Average Remaining Contractual Life (in years)	1 year 36 days	1 year 256 days	2 years 182 days	2 years 328 days