Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note [Abstract]

Changes To Equity

Shares of our common stock outstanding and activity for the years ended December 31, 2015, 2014 and 2013 are presented below:

	Years Ended December 31,
	2015		2014		2013
Common shares outstanding at January 1	196,086,090		198,830,351		203,551,496
Issuance of restricted stock, excluding restricted stock with performance feature	447,534		376,622		292,855
Vesting of performance units	136,896		416,111		210,819
Vesting of restricted stock with performance feature	43,774		77,430		15,141
Forfeitures of restricted stock	(51,332	)	(76,107	)	(15,794	)
Purchase of treasury stock (1)	(16,428,574	)	(3,538,317	)	(5,224,166	)
Common shares outstanding at December 31	180,234,388		196,086,090		198,830,351

(1) Includes 151,967, 279,680 and 235,922 shares, respectively, withheld under the terms of stock-based compensation agreements to provide funds for the payment of payroll and income taxes due at the vesting of share-based awards, as well as other stock repurchases under separate authority from our Board of Directors.