Basis and Summary of Significant Accounting Policies - Calculation of Dilutive Stock Awards (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accounting Policies [Abstract]
Weighted average shares outstanding	72,761	72,572	72,697	72,544
Dilutive effect of share-based awards (in shares)	518	393	551	366
Weighted average shares outstanding assuming dilution	73,279	72,965	73,248	72,910
Anti-dilutive securities excluded from the computation of earnings per share assuming dilution (in shares)	1,265	545	1,057	507