Stock-Based Compensation Restricted Stock Units Summary (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Restricted Stock Units (RSUs) [Member]
[Line Items]
Outstanding, beginning balance, Number		756,000		682,000		658,000
Granted, Number		306,000	[1]	434,000	[2]	350,000	[3]
Weighted-average grant date fair value		$ 41.58		$ 35.09		$ 35.74
Forfeited, Number		(82,000)		(64,000)		(35,000)
Outstanding, ending balance, Number		668,000		756,000		682,000
Long Term Performance Restricted Stock Award [Member]
[Line Items]
Granted, Number		110,259		15,648		14,433
Vested and Released [Member] | Restricted Stock Units (RSUs) [Member]
[Line Items]
Issued, Number		(312,000)		(296,000)		(291,000)
Released, Aggregate Intrinsic Value	[4]	$ 11,944		$ 12,204		$ 14,402
Vested but Not Released [Member] | Restricted Stock Units (RSUs) [Member]
[Line Items]
Issued, Number		(115,000)
Vested but not released, Aggregate Intrinsic Value	[4]	$ 7,242
Expected to Vest [Member] | Restricted Stock Units (RSUs) [Member]
[Line Items]
Outstanding, ending balance, Number		477,000
Expected to vest, Aggregate Intrinsic Value	[4]	$ 30,006

[1] Restricted stock units include 110,259 shares for the 3-year award under the 2014 Performance Award Agreement, which are eligible for distribution at December 31, 2016.

[2] Restricted stock units include 15,648 shares for the 3-year award under the 2013 Performance Award Agreement, which are eligible for distribution at December 31, 2015.

[3] Restricted stock units include 14,433 shares for the 2-year award under the 2013 Performance Award Agreement, which are eligible for distribution at December 31, 2014.

[4] 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.