Stock-based Compensation - Schedule of Non-Vested RSUs (Detail) shares in Thousands	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Nonvested Restricted Stock Units Activity [Line Items]
Non-vested, beginning balance | shares	2,083
Shares, Granted | shares	491
Shares, Vested | shares	(391)
Shares, Forfeited | shares	(438)
Non-vested, ending balance | shares	1,745
Weighted average grant date fair value, Non-vested, beginning balance | $ / shares	$ 43.34
Weighted average grant date fair value, Granted | $ / shares	46.70
Weighted average grant date fair value, Vested | $ / shares	41.58
Weighted average grant date fair value, Forfeited | $ / shares	41.14
Weighted average grant date fair value, Non-vested, ending balance | $ / shares	$ 45.23
Time-based RSUs [Member]
Nonvested Restricted Stock Units Activity [Line Items]
Non-vested, beginning balance | shares	795
Shares, Granted | shares	120
Shares, Vested | shares	(128)
Shares, Forfeited | shares	(35)
Non-vested, ending balance | shares	752
Weighted average grant date fair value, Non-vested, beginning balance | $ / shares	$ 43.79
Weighted average grant date fair value, Granted | $ / shares	45.98
Weighted average grant date fair value, Vested | $ / shares	43.43
Weighted average grant date fair value, Forfeited | $ / shares	43.50
Weighted average grant date fair value, Non-vested, ending balance | $ / shares	$ 44.22
Performance-based RSUs [Member]
Nonvested Restricted Stock Units Activity [Line Items]
Non-vested, beginning balance | shares	1,265
Shares, Granted | shares	371
Shares, Vested | shares	(263)
Shares, Forfeited | shares	(403)
Non-vested, ending balance | shares	970
Weighted average grant date fair value, Non-vested, beginning balance | $ / shares	$ 42.64
Weighted average grant date fair value, Granted | $ / shares	46.93
Weighted average grant date fair value, Vested | $ / shares	40.67
Weighted average grant date fair value, Forfeited | $ / shares	40.93
Weighted average grant date fair value, Non-vested, ending balance | $ / shares	$ 45.52
Market-based RSUs [Member]
Nonvested Restricted Stock Units Activity [Line Items]
Non-vested, beginning balance | shares	23
Non-vested, ending balance | shares	23
Weighted average grant date fair value, Non-vested, beginning balance | $ / shares	$ 33.16
Weighted average grant date fair value, Non-vested, ending balance | $ / shares	$ 33.16