Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Taxes And Tax Related [Line Items]
Valuation allowance	$ 4,200,000
Effective tax rate	37.30%	0.90%
Income tax expense	7,327,000	198,000
Excess tax benefits from stock-based awards	$ 6,500,000
Minimum [Member] | Federal Tax Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination	2010
Minimum [Member] | State and Local Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination	2008
Minimum [Member] | Michigan [Member]
Income Taxes And Tax Related [Line Items]
Tax examination year under examination	2008
Maximum [Member] | Federal Tax Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination	2013
Maximum [Member] | State and Local Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination	2013
Maximum [Member] | Michigan [Member]
Income Taxes And Tax Related [Line Items]
Tax examination year under examination	2011