Share-Based Compensation Arrangements (Nonvested Performance Shares Outstanding) (Details) - Performance Based Nonvested Shares [Member]	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards, shares vesting	110,891
2015 Grant [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards granted, grant date fair value | $ / shares	$ 38.02
Performance share awards, shares vesting percentages	152.00%
Performance share awards, shares vesting	47,451
2014 Grant [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards granted, grant date fair value | $ / shares	$ 34.66
Performance share awards, shares vesting percentages	139.00%
Performance share awards, shares vesting	21,049
2013 Grant [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards granted, grant date fair value | $ / shares	$ 26.05
Performance share awards, shares vesting percentages	141.00%
Performance share awards, shares vesting	42,391