Share-Based Compensation (Detail) - Restricted Stock Award Transactions shares in Thousands	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Restricted Stock And Restricted Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards at beginning of year (in shares) | shares	997
Granted (in shares) | shares	453
Vested (in shares) | shares	(483)
Forfeited (in shares) | shares	(59)
Non-vested awards at end of year (in shares) | shares	908
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested awards at beginning of year (in dollars per share) | $ / shares	$ 13.79
Granted (in dollars per share) | $ / shares	16.95
Vested (in dollars per share) | $ / shares	12.54
Forfeited (in dollars per share) | $ / shares	15.07
Non-vested awards at end of year (in dollars per share) | $ / shares	$ 15.92
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards at beginning of year (in shares) | shares	238
Granted (in shares) | shares	112
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(12)
Non-vested awards at end of year (in shares) | shares	338
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested awards at beginning of year (in dollars per share) | $ / shares	$ 14.36
Granted (in dollars per share) | $ / shares	16.95
Vested (in dollars per share) | $ / shares	0.00
Forfeited (in dollars per share) | $ / shares	15.07
Non-vested awards at end of year (in dollars per share) | $ / shares	$ 15.19