Shareholders' Equity - Common Stock and Treasury Stock Period Activity (Details) shares in Thousands		12 Months Ended
	Jun. 14, 2017	Dec. 31, 2017 shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition of Treasury stock		173,807
Stockholders' Equity Note, Stock Split, Conversion Ratio	0.25
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, Beginning		253,594	253,209	281,089
Stock based compensation plans, net		1,019	385	2,823
Acquisition of Treasury stock				0
Cancellation of Treasury stock				(30,703)
Balance, Ending		254,613	253,594	253,209
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, Beginning		0	0	1,903
Stock based compensation plans, net		0	0	0
Acquisition of Treasury stock				28,800
Cancellation of Treasury stock				(30,703)
Balance, Ending		0	0	0