Share-Based Compensation and Equity - Director Deferred Shares Activity (Details) (Director Deferred Shares [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion to common stock (shares)	1
Non-employee director deferred shares vested and outstanding	143,000
Granted, Weighted-average grant-date fair value		$ 29.73	$ 40.54
Aggregate intrinsic value of deferred shares released	$ 121	$ 1,023	$ 247
Total fair value of deferred shares vested	$ 898	$ 1,090	$ 979
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	12 months