Stock-based Compensation - Summary of Terms of Restricted Shares (Detail) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares	2,517
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares	900	770
Weighted Average Grant- date Fair Value	$ 15.45	$ 19.58
Restricted Stock [Member] \| 1/3rd per year on grant-date anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	433
Weighted Average Grant- date Fair Value	$ 15.81
Restricted Stock [Member] \| 1/3rd per year on grant-date anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	22
Weighted Average Grant- date Fair Value	$ 15.95
Restricted Stock [Member] \| 1/3rd per year on grant-date anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	445
Weighted Average Grant- date Fair Value	$ 15.08
Restricted Stock [Member] \| 1/3rd per year on grant-date anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	465
Weighted Average Grant- date Fair Value	$ 20.02
Restricted Stock [Member] \| Share Based Compensation Award Tranche Two Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	305
Weighted Average Grant- date Fair Value	$ 18.90
Restricted Stock [Member] \| Share Based Compensation Award Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/4th on the 1st grant-date anniversary and 3/4th on the 2nd grant-date anniversary
Number of Shares	567
Weighted Average Grant- date Fair Value	$ 15.00
Restricted Stock [Member] \| Share Based Compensation Award Tranche Two Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Terms	1/3rd per year on grant-date anniversary
Number of Shares	280
Weighted Average Grant- date Fair Value	$ 15.00

Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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+ References

No definition available.

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