Basis and Summary of Significant Accounting Policies - Calculation of Dilutive Stock Awards (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accounting Policies [Abstract]
Weighted average shares outstanding	72,586	72,340	72,558	72,350
Dilutive effect of share-based awards (in shares)	490	320	408	363
Weighted average shares outstanding assuming dilution	73,076	72,660	72,966	72,713