Employee Benefit Plans - Summary of Pension Plan Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	$ 54,155		$ 53,080
Investments in equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	28,390		29,152
Investments in equity securities | Us Large Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	8,097	[1]	8,082	[1]
Investments in equity securities | Us Mid Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	3,447	[1]	3,412	[1]
Investments in equity securities | United States Equity Small Cap
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,694	[1]	1,736	[1]
Investments in equity securities | International All Cap Equity
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	9,621	[2]	10,687	[2]
Investments in equity securities | Alternative Strategies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	5,531	[3]	5,235	[3]
Debt securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	20,375		19,396
Debt securities | Us Treasury Inflation Protected Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets			2,462
Debt securities | Fixed Income
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	17,717	[4]	14,305	[4]
Debt securities | High Yield Asset Backed Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	2,658	[4]	2,629	[4]
Other
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	5,390		4,532
Other | Commodities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,819	[5]	1,939	[5]
Other | Real Estate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	2,427	[6]	1,991	[6]
Other | Guaranteed deposit
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,144	[7]	602	[7]
Quoted Prices in Active Markets (Level 1)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	46,448		26,278
Quoted Prices in Active Markets (Level 1) | Investments in equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	21,827		19,886
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Us Large Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	4,069	[1]	3,964	[1]
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Us Mid Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,733	[1]	0	[1]
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | United States Equity Small Cap
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	873	[1]	0	[1]
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | International All Cap Equity
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	9,621	[2]	10,687	[2]
Quoted Prices in Active Markets (Level 1) | Investments in equity securities | Alternative Strategies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	5,531	[3]	5,235	[3]
Quoted Prices in Active Markets (Level 1) | Debt securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	20,375		2,462
Quoted Prices in Active Markets (Level 1) | Debt securities | Us Treasury Inflation Protected Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets			2,462
Quoted Prices in Active Markets (Level 1) | Debt securities | Fixed Income
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	17,717	[4]	0	[4]
Quoted Prices in Active Markets (Level 1) | Debt securities | High Yield Asset Backed Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	2,658	[4]	0	[4]
Quoted Prices in Active Markets (Level 1) | Other
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	4,246		3,930
Quoted Prices in Active Markets (Level 1) | Other | Commodities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,819	[5]	1,939	[5]
Quoted Prices in Active Markets (Level 1) | Other | Real Estate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	2,427	[6]	1,991	[6]
Quoted Prices in Active Markets (Level 1) | Other | Guaranteed deposit
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[7]	0	[7]
Significant Other Observable Inputs (Level 2)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	6,563		26,200
Significant Other Observable Inputs (Level 2) | Investments in equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	6,563		9,266
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Us Large Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	4,028	[1]	4,118	[1]
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Us Mid Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,714	[1]	3,412	[1]
Significant Other Observable Inputs (Level 2) | Investments in equity securities | United States Equity Small Cap
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	821	[1]	1,736	[1]
Significant Other Observable Inputs (Level 2) | Investments in equity securities | International All Cap Equity
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[2]	0	[2]
Significant Other Observable Inputs (Level 2) | Investments in equity securities | Alternative Strategies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[3]	0	[3]
Significant Other Observable Inputs (Level 2) | Debt securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0		16,934
Significant Other Observable Inputs (Level 2) | Debt securities | Us Treasury Inflation Protected Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets			0
Significant Other Observable Inputs (Level 2) | Debt securities | Fixed Income
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[4]	14,305	[4]
Significant Other Observable Inputs (Level 2) | Debt securities | High Yield Asset Backed Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[4]	2,629	[4]
Significant Other Observable Inputs (Level 2) | Other
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0		0
Significant Other Observable Inputs (Level 2) | Other | Commodities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[5]	0	[5]
Significant Other Observable Inputs (Level 2) | Other | Real Estate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[6]	0	[6]
Significant Other Observable Inputs (Level 2) | Other | Guaranteed deposit
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[7]	0	[7]
Significant Unobservable Inputs (Level 3)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,144		602		710
Significant Unobservable Inputs (Level 3) | Investments in equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0		0
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Us Large Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Us Mid Cap Equity Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) | Investments in equity securities | United States Equity Small Cap
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) | Investments in equity securities | International All Cap Equity
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[2]	0	[2]
Significant Unobservable Inputs (Level 3) | Investments in equity securities | Alternative Strategies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[3]	0	[3]
Significant Unobservable Inputs (Level 3) | Debt securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0		0
Significant Unobservable Inputs (Level 3) | Debt securities | Us Treasury Inflation Protected Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets			0
Significant Unobservable Inputs (Level 3) | Debt securities | Fixed Income
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[4]	0	[4]
Significant Unobservable Inputs (Level 3) | Debt securities | High Yield Asset Backed Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[4]	0	[4]
Significant Unobservable Inputs (Level 3) | Other
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	1,144		602
Significant Unobservable Inputs (Level 3) | Other | Commodities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[5]	0	[5]
Significant Unobservable Inputs (Level 3) | Other | Real Estate
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	0	[6]	0	[6]
Significant Unobservable Inputs (Level 3) | Other | Guaranteed deposit
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total Pension Plan Assets	$ 1,144	[7]	$ 602	[7]

[1] Includes funds that invest primarily in United States common stocks.

[2] Includes funds that invest primarily in foreign equities and emerging markets equities.

[3] Includes funds that actively invest in both equity and debt securities, funds that sell short securities and funds that provide long-term capital appreciation. The funds may invest in debt securities below investment grade.

[4] Includes funds that invest in investment grade and fixed income securities.

[5] Includes funds that invest primarily in commodity-linked derivative instruments and fixed income securities.

[6] Includes funds that invest primarily in real estate.

[7] Includes investment in a group annuity product issued by an insurance company.