Changes in Outstanding Common Stock (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Outstanding, beginning of year (in shares)	99,377	99,204	98,031
Shares issued upon exercise of options (in shares)	125	104	540
Shares issued for time vested restricted stock (net of cancellations) (in shares)	341	69	633
Outstanding, end of year (in shares)	99,843	99,377	99,204