Stock-Based Compensation Restricted Stock Units Summary (Details) (Restricted Stock Units (RSUs) [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
[Line Items]
Outstanding, beginning balance, Number	658		774
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	330	[1]	255	[1]
Weighted-average fair value	$ 35.64	[1]	$ 42.51	[1]
Forfeited, Number	(29)		(27)
Outstanding, ending balance, Number	693		742
Vested and Released [Member]
[Line Items]
Released, Number	(266)		(260)
Released, Aggregate Intrinsic Value	$ 13,022	[2]	$ 13,860	[2]
Vested but Not Released [Member]
[Line Items]
Released, Number	(10)
Released, Aggregate Intrinsic Value	383	[2]
Expected to Vest [Member]
[Line Items]
Outstanding, ending balance, Number	588
Expected to vest, Aggregate Intrinsic Value	$ 23,125	[2]

[1] Restricted stock units granted in 2013 and 2014 do not include awards under the Performance Award Agreement for the respective years, as these awards are not granted until attainment of annual performance goals has been determined at the conclusion of the performance period, which had not occurred as of September 30, 2013 and 2014, respectively.

[2] The aggregate intrinsic value is the market value of the stock, before applicable income taxes, based on the closing price on the stock release dates or at the end of the period for restricted stock units expected to vest.