8	EXCHANGEABLE SENIOR NOTES

In October 2006, the Company issued $200,000 principal amount of exchangeable senior notes ("Senior Notes") under an Indenture, with a coupon rate of 4.125%. In the fourth quarter of 2008, the Company repurchased $60,000 principal amount of the Senior Notes, leaving $140,000 outstanding. The Senior Notes were exchangeable into cash equal to the principal amount of the notes and, at the Company's option, cash or common stock for the exchange value, to the extent that the market price of common stock exceeded the initial exchange price of $73.34 per share, subject to adjustment and generally not redeemable by the Company until November 1, 2011. Prior to the maturity date of November 1, 2026, holders of the Senior Notes had the right to require the Company to repurchase the notes on November 1, 2011, 2016 and 2021, and the occurrence of certain events.

On November 1, 2011, the Company repurchased at face value $135,000 of the Senior Notes, plus accrued interest of $2,784, that were presented by the holders for repurchase in accordance with the Indenture. On December 21, 2011 the remaining outstanding balance of $5,000 principal amount of the Senior Notes was repurchased by the Company, at face value plus accrued interest of $29, at the Company's option in accordance with the Indenture. There were no outstanding Senior Notes as of December 31, 2011.

The following table provides additional information about the Senior Notes as of December 31, 2010:


	2010
Principal amount of liability component	$	140,000
Unamortized discount		(1,782	)

Carrying amount of liability component	$	138,218

Carrying amount of equity component	$	13,950

The following table provides additional information about the Senior Notes for the years ended December 31, 2011, 2010 and 2009:


	2011		2010		2009
Coupon interest	$	4,835	$	5,775	$	5,775
Issuance cost amortization		456		547		547
Discount amortization		1,782		2,082		1,968

Total interest expense	$	7,073	$	8,404	$	8,290

The effective interest rate was 5.75% for the years ended 2011, 2010 and 2009. The conversion price per share, as adjusted, was $72.87 for the years ended 2010 and 2009 and as of the November 1, 2011 and December 21, 2011 repurchase dates.