Earnings Per Share (Details) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Average common shares outstanding - basic (in shares)	123,599	123,033	123,417	122,891
Effect of dilutive securities - share-based compensation (in shares)	786	728	885	836
Average common shares - diluted (in shares)	124,385	123,761	124,302	123,727
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	1,070	1,479	1,070	658
Employee and director share options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	53	42	53	42
Restricted shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	0	821	0	0
Share appreciation rights [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	1,017	616	1,017	616