Segment Reporting (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Sales	$ 219,542,000	$ 213,176,000	$ 435,883,000	$ 427,617,000
Revenue from Related Parties	0	0	0	0
Total sales	219,542,000	213,176,000	435,883,000	427,617,000
Operating income	31,809,000	22,130,000	53,753,000	40,055,000
Depreciation and amortization expense	8,925,000	9,465,000	17,399,000	18,851,000
Litigation Settlement, Expense				7,200,000
Prior Period Reclassification Adjustment				1,600,000
Specialty Phosphates US & Canada [Member]
Segment Reporting Information [Line Items]
Sales	157,267,000	159,054,000	308,277,000	310,045,000
Revenue from Related Parties	796,000	778,000	1,550,000	1,301,000
Total sales	158,063,000	159,832,000	309,827,000	311,346,000
Operating income	21,334,000	23,759,000	41,547,000	34,551,000
Depreciation and amortization expense	6,291,000	6,465,000	11,609,000	13,572,000
Specialty Phosphates Mexico [Member]
Segment Reporting Information [Line Items]
Sales	40,885,000	43,370,000	85,374,000	82,285,000
Revenue from Related Parties	15,139,000	14,860,000	27,757,000	27,123,000
Total sales	56,024,000	58,230,000	113,131,000	109,408,000
Operating income	10,320,000	1,333,000	16,181,000	1,990,000
Depreciation and amortization expense	2,277,000	2,318,000	5,046,000	4,076,000
GTSP & Other [Member]
Segment Reporting Information [Line Items]
Sales	21,390,000	10,752,000	42,232,000	35,287,000
Revenue from Related Parties	38,000	128,000	39,000	239,000
Total sales	21,428,000	10,880,000	42,271,000	35,526,000
Operating income	155,000	(2,962,000)	(3,975,000)	3,514,000
Depreciation and amortization expense	357,000	682,000	744,000	1,203,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Revenue from Related Parties	(15,973,000)	(15,766,000)	(29,346,000)	(28,663,000)
Total sales	(15,973,000)	(15,766,000)	(29,346,000)	(28,663,000)
Operating income	0	0	0	0
Depreciation and amortization expense	0	0	0	0
Cost of Sales [Member]
Segment Reporting Information [Line Items]
Prior Period Reclassification Adjustment				$ 2,300,000