Share-Based Compensation and Equity - Director Deferred Shares Activity (Details) (Director Deferred Shares [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Director Deferred Shares [Member]
Director Deferred Shares
Unvested, Shares, Beginning balance	20
Unvested, Weighted-average grant-date fair value, Beginning balance	$ 40.54
Forfeited, Shares	(3)
Forfeited, Weighted-average grant-date fair value	$ 40.54
Vested, Shares	(31)
Vested, Weighted-average grant-date fair value	$ 35.80
Granted, Shares	44
Granted, Weighted-average grant-date fair value	$ 29.73	$ 40.54	$ 33.98
Unvested, Shares, Ending balance	30	20
Unvested, Weighted-average grant-date fair value, Ending balance	$ 29.73	$ 40.54
Vested, Shares, Ending balance	116
Vested Shares, Weighted Average grant-date fair value, ending balance	$ 34.88
Outstanding, Shares, Ending balance	146
Outstanding Shares, Weighted Average grant-date fair value, ending balance	$ 33.81
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Released Intrinsic Value	$ 1,023	$ 247	$ 247
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 1,090	$ 979	$ 887