Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accounts receivable, allowances	$ 33,133	$ 35,087
Preferred stock, par value (usd per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	260,000,000	260,000,000
Common stock, issued (in shares)	127,796,558	131,156,064
Common stock, outstanding (in shares)	127,796,558	131,156,064