Share-Based Compensation Arrangements (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Share Options [Member]	Dec. 31, 2012 Share Options [Member]	Dec. 31, 2011 Share Options [Member]	Dec. 31, 2013 Time Based Nonvested Shares [Member]	Dec. 31, 2012 Time Based Nonvested Shares [Member]	Dec. 31, 2011 Time Based Nonvested Shares [Member]	Dec. 31, 2013 Performance Based Nonvested Shares [Member]	Dec. 31, 2012 Performance Based Nonvested Shares [Member]	Dec. 31, 2011 Performance Based Nonvested Shares [Member]	Dec. 31, 2012 Minimum [Member] Share Options [Member]	Dec. 31, 2013 Minimum [Member] Time Based Nonvested Shares [Member]	Dec. 31, 2012 Minimum [Member] Time Based Nonvested Shares [Member]	Dec. 31, 2013 Minimum [Member] Performance Based Nonvested Shares [Member]	Dec. 31, 2012 Maximum [Member] Share Options [Member]	Dec. 31, 2013 Maximum [Member] Time Based Nonvested Shares [Member]	Dec. 31, 2012 Maximum [Member] Time Based Nonvested Shares [Member]	Dec. 31, 2013 Maximum [Member] Performance Based Nonvested Shares [Member]	Apr. 23, 2013 2013 Stock Option and Incentive Plan [Member]	Apr. 22, 2003 Two Thousand Three Stock Incentive Plan [Member]	Apr. 22, 2003 Two Thousand Three Stock Incentive Plan [Member] Stock Options and Stock Appreciation Rights [Member]	Apr. 28, 2009 Amended and Restated Two Thousand Three Stock Incentive Plan [Member]	Apr. 28, 2009 Amended and Restated Two Thousand Three Stock Incentive Plan [Member] Stock Options and Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized																			1,748,250	600,000	200,000	1,200,000	400,000
Expiration period		10 years
Equity instruments other than options minimum shares earned to target percentage														0.00%
Equity instruments other than options maximum shares earned to target percentage																		200.00%
Options granted		54,600	106,775	57,450
Award vesting period		3 years		3 years			3 years	3 years	3 years	3 years	3 years	3 years	3 years		5 years	5 years	5 years
Share options exercised total intrinsic value		$ 1,700,000	$ 812,000	$ 493,000
Equity instruments other than options granted					24,400	29,725	31,950	49,138
Equity instruments other than options granted, grant date fair value								$ 26.05	$ 23.65	$ 21.62
Equity instruments other than options, shares vesting percentages								150.00%	154.00%	150.00%
Equity instruments other than options, shares vesting								45,225	38,654	40,238
Total unrecognized compensation cost	$ 3,200,000
Weighted average recognition period (in years)	2 years 1 month