Stock-Based Compensation - Summary of Stock Option Activity under 2006 EIP and 2013 LTIP (Detail)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	(16,444)
2006 EIP and 2013 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Available for Grant, Beginning Balance	5,333,520
Options Available for Grant, Options exercised	0
Restricted stock granted	(679,594)
Restricted stock canceled	66,265
Options Available for Grant, Ending Balance	4,736,279
Number of Shares, Beginning Balance	2,169,305
Number of Shares, Options Exercised	(20,549)
Number of Shares, Ending Balance	1,973,454
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 27.45
Weighted Average Exercise Price, Exercised | $ / shares	24.79
Weighted Average Exercise Price, Ending Balance | $ / shares	$ 27.24
2013 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Available for Grant, Options Canceled or forfeited	16,088
Number of Shares, Options Canceled or forfeited	(16,088)
Weighted Average Exercise Price, Options Canceled or forfeited | $ / shares	$ 23.40
2006 EIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Available for Grant, Options Canceled or forfeited	0
Number of Shares, Options Canceled or forfeited	(159,214)
Weighted Average Exercise Price, Options Canceled or forfeited | $ / shares	$ 30.84