Share-Based Compensation and Equity - Restricted Stock Unit Activity (Details) (Restricted Stock Units [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Restricted Stock Units
Unvested, Shares, Beginning balance	499
Unvested, Weighted-average grant-date fair value, Beginning balance	$ 32.28
Forfeited, Shares	(62)
Forfeited, Weighted-average grant-date fair value	$ 32.90
Vested, Shares	(134)
Vested, Weighted-average grant-date fair value	$ 32.72
Granted, Shares	350	[1]
Granted, Weighted-average grant-date fair value	$ 35.25	[1]	$ 30.14	$ 35.16
Unvested, Shares, Ending balance	653		499
Unvested, Weighted-average grant-date fair value, Ending balance	$ 33.72		$ 32.28
One year vest [Member]
Restricted Stock Units
Granted, Shares	35
Granted, Weighted-average grant-date fair value	$ 39.35

[1] The RSUs granted during the year ended December 31, 2014 include 35 thousand one-year RSUs to non-employee directors under the 1991 Plan. These RSUs have a weighted-average grant-date fair value of $39.35